Type 1 Diabetes MellitusT1TempNCT07491133
Effect of Ambient Temperature on Blood Glucose and Insulin Absorption in Adults With Type 1 Diabetes
A study testing Environmental Temperature Exposure in people with Type 1 Diabetes Mellitus, run by Institut de Recherches Cliniques de Montreal at 1 site in Canada.
Trial summary
The goal of this clinical trial is to learn how different temperatures affect blood sugar levels in adults with type 1 diabetes. Climate change is causing more extreme hot and cold weather, and people with type 1 diabetes may be at higher risk during these temperature changes. Read more about this study
- Who is it for?
- Ages 18 to 45 years
- Conditions the study is for
- Type 1 Diabetes Mellitus
- What is being tested?
- Environmental Temperature Exposure
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteCanada
- Study dates
- Mar 2026to Jul 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 45 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Diagnosis of type 1 diabetes for more than 2 years
- Ability to provide verbal and written informed consent
- Ability to speak and understand French
Who cannot join
- Recent and/or unstable health condition (less than 3 months) prior to enrolment
- Any viral infection at time of participation
- Chronic illness other than type 1 diabetes (for example: pulmonary disease, cardiovascular disease, cancer)
- Health condition not controlled by medication
- Pregnancy or breastfeeding (for female participants)
- Any other health condition deemed to pose undue health risks during participation in the study
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site
Institut de recherches cliniques de Montréal
Montreal, Quebec, H2W 1R7
About this study
Official title: Effect of Ambient Temperature on Insulin Absorption and Change in Blood Glucose Levels in Individuals With Type 1 Diabetes
The goal of this clinical trial is to learn how different temperatures affect blood sugar levels in adults with type 1 diabetes. Climate change is causing more extreme hot and cold weather, and people with type 1 diabetes may be at higher risk during these temperature changes. The main questions it aims to answer are:
- Do different temperatures (cold, normal, or hot) change blood sugar levels in people with type 1 diabetes?
- How does temperature affect insulin absorption in the body?
Read more
Researchers will compare three different temperature conditions to see how each affects blood sugar levels and insulin in the body.
Participants will:
- Complete a screening visit with body measurements and questionnaires
- Attend 3 separate study visits, each in a different temperature setting:
- Cold room (10°C/50°F)
- Normal room temperature (23°C/73°F)
- Hot and humid room (36°C/97°F with 65% humidity)
- Sit for 2 hours in each temperature condition while researchers monitor their blood sugar, heart rate, and body temperature
- Wear a continuous glucose monitor for 48-72 hours before each visit
- Keep a diary of food, sleep, and activity for 24 hours before and after each visit
Each temperature visit is separated by at least 3 days. The study helps researchers understand if people with type 1 diabetes need special guidance for managing their blood sugar during extreme weather.
Read the detailed description
Background and Rationale
Climate change is increasing the frequency of extreme weather events, including heat waves and cold snaps. People with type 1 diabetes face higher risks of illness and death during these extreme temperature periods compared to people without diabetes. However, the reasons for this increased risk are not well understood.
When insulin is injected under the skin, it forms a small reservoir from which it gradually enters the bloodstream. Temperature may affect how quickly this insulin is absorbed. Warmer temperatures increase blood flow to the skin, which could speed up insulin absorption and potentially cause blood sugar to drop too low (hypoglycemia). Colder temperatures might slow insulin absorption, leading to higher blood sugar levels (hyperglycemia).
Previous research from the 1980s showed that heating or cooling the injection site affects insulin absorption, but these studies were conducted before modern rapid-acting insulins and diabetes technologies like insulin pumps and continuous glucose monitors were available. No recent studies have examined how whole-body temperature exposure affects insulin absorption and blood sugar control in people with type 1 diabetes.
Study Design Overview
This is a randomized, crossover clinical trial where each participant will experience all three temperature conditions in random order. The study includes:
- 1 preliminary visit for screening and measurements
- 3 experimental visits (cold, neutral, hot conditions)
- Total participation time: approximately 14 hours over up to 4 months
Study Population
The study will enroll 30 adults aged 18-45 years with type 1 diabetes for at least 2 years. Participants will be equally divided by:
- Sex: 50% male, 50% female
- Insulin delivery method: 10 using multiple daily injections, 10 using insulin pumps, 10 using hybrid closed-loop systems
Preliminary Visit Procedures
During the first visit at the Montreal Clinical Research Institute (IRCM), participants will:
- Review and sign informed consent documents
- Complete medical history and lifestyle questionnaires
- Fill out a heat exposure questionnaire based on Health Canada guidelines
- Complete the GENESIS PRAXY questionnaire to document gender-related factors
- Undergo body measurements including height, weight, waist circumference, and body composition scan
- Have resting heart rate and blood pressure measured
- Receive training on continuous glucose monitor use (if not already using one)
Experimental Visit Procedures
Each of the three experimental visits will take place at Centre ÉPIC and follow the same protocol in different temperature conditions:
Pre-Exposure Phase (60 minutes)
- Participants arrive 2 hours after eating a standardized snack (100g Greek yogurt) with their usual insulin dose
- Body weight measurement
- Installation of rectal temperature probe (self-inserted privately)
- Placement of intravenous catheter for blood sampling
- Attachment of skin temperature sensors, blood pressure cuff, and heart rate monitor
- 60-minute rest period at room temperature to establish baseline measurements
Temperature Exposure Phase (120 minutes)
Participants will sit in an environmental chamber set to one of three conditions:
- Cold: 10°C (50°F) - causes shivering and increases energy expenditure by approximately 80%
- Neutral: 23°C (73°F) - comfortable room temperature
- Hot/Humid: 36°C (97°F) with 65% humidity - simulates a hot summer day in Montreal
Measurements During Exposure
Continuous monitoring:
- Heart rate via chest strap monitor
- Core body temperature via rectal probe
- Skin temperature at four sites (arm, chest, thigh, calf)
- Blood sugar levels via continuous glucose monitor (checked every 15 minutes)
Intermittent measurements:
- Blood pressure every 10 minutes
- Blood samples at baseline, 60 minutes, and 120 minutes for analysis of glucose, insulin, glucagon, and other metabolic markers
- Comfort and sensation ratings every 10 minutes using visual scales for thermal comfort, thermal sensation, and thirst
Safety Monitoring
Throughout each visit, research staff will continuously monitor participants for:
- Signs of hypoglycemia (low blood sugar) - treated immediately with glucose if needed
- Core body temperature limits (stopped if ≤35.5°C during cold or ≥39.5°C during heat exposure)
- Blood pressure limits (stopped if >180/110 mmHg or <90/60 mmHg)
- Participant comfort and willingness to continue
Data Collection
24-Hour Activity Logs
Participants will record their food intake, insulin doses, sleep patterns, and physical activity for:
- 48 hours before the preliminary visit (baseline lifestyle)
- 24 hours before each experimental visit
- 24 hours after each experimental visit
Continuous Glucose Monitoring
A Dexcom G7 sensor will be installed 48-72 hours before each visit to capture:
- Glucose patterns during temperature exposure
- 24-hour glucose control before and after each visit
- Time spent in target range (3.9-10.0 mmol/L)
- Time spent above target (>10.0 mmol/L)
- Time spent below target (<3.9 mmol/L)
Laboratory Analyses
Blood samples will be analyzed for:
- Plasma glucose and insulin levels
- Glucagon (hormone that raises blood sugar)
- Free fatty acids and glycerol (markers of fat metabolism)
- Other metabolic hormones
Special Considerations
For Female Participants Study visits will be scheduled during the follicular phase of the menstrual cycle (or placebo pill phase for those using oral contraceptives) since hormonal changes can affect blood sugar levels.
Insulin Delivery Methods The study will examine whether different insulin delivery methods (injections, pumps, or automated systems) respond differently to temperature changes.
Participant Safety and Comfort
- At least two research staff members will be present during each visit
- One staff member will remain in the environmental chamber with the participant
- Participants can request to stop the exposure at any time
- Emergency procedures are in place for severe blood sugar episodes
- Socks and gloves will be provided during cold exposure if needed
Study Significance
This research will provide the first modern evidence about how environmental temperature affects insulin absorption and blood sugar control in people with type 1 diabetes. The findings could lead to new clinical guidelines for diabetes management during extreme weather events, potentially reducing the increased health risks that people with type 1 diabetes face during heat waves and cold snaps.
The study results may inform recommendations for insulin dose adjustments during temperature extremes and help health care providers better advise patients with type 1 diabetes about managing their condition during increasingly frequent extreme weather events related to climate change.
- Conditions
- Type 1 Diabetes Mellitus
- Being tested
- Environmental Temperature Exposure
- Keywords
- Type 1 diabetes, Insulin absorption, Temperature exposure, Blood glucose, Continuous glucose monitoring, Hypoglycemia
- Medical subject headings
- Diabetes Mellitus, Type 1, Hypoglycemia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Environmental Temperature ExposureOther
Also called Temperature Stress Testing, Thermal Exposure Protocol, Environmental Chamber Study, Ambient Temperature Intervention
Systematic exposure to controlled temperature and humidity conditions in a specialized environmental chamber. Each exposure lasts 120 minutes with participants remaining seated throughout. All exposures include standardized pre-exposure preparation (60-minute baseline period at room temperature), continuous physiological monitoring, standardized clothing, and identical blood sampling schedules. Safety protocols include continuous staff supervision, predetermined stopping criteria for extreme body temperatures or blood pressure changes, and immediate availability of warming/cooling interventions and hypoglycemia treatment protocols.
| Study group | Role | What they receive |
|---|---|---|
| Cold exposure | Experimental | Participants will be exposed to cold temperature (10°C/50°F) in an environmental chamber for 120 minutes while seated. This temperature is designed to induce shivering thermogenesis and increase energy expenditure by approximately 80%. The cold exposure may slow insulin absorption from subcutaneous injection sites due to reduced skin blood flow and vasoconstriction. Participants will wear standard clothing (shorts and t-shirt) with optional socks and gloves if needed for comfort. Continuous monitoring includes core body temperature via rectal probe, skin temperature at four sites, heart rate, blood pressure every 10 minutes, and blood glucose via continuous glucose monitor every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes for plasma glucose, insulin, glucagon, and metabolic markers. The exposure will be terminated if core body temperature drops to ≤35.5°C. Receives: Other: Environmental Temperature Exposure |
| Neutral Temperature | Active comparator | Participants will be exposed to neutral room temperature (23°C/73°F) in an environmental chamber for 120 minutes while seated. This condition serves as the control/reference temperature representing typical indoor environmental conditions. At this temperature, normal thermoregulatory responses are minimal, allowing assessment of baseline insulin absorption and glucose responses without temperature-induced physiological stress. Participants will wear standard clothing (shorts and t-shirt) and undergo the same monitoring protocol as other arms: continuous core and skin temperature measurement, heart rate monitoring, blood pressure every 10 minutes, blood glucose monitoring every 15 minutes via continuous glucose monitor, and blood sampling at baseline, 60 minutes, and 120 minutes. Receives: Other: Environmental Temperature Exposure |
| Hot/Humid Exposure | Experimental | Participants will be exposed to hot and humid conditions (36°C/97°F with 65% relative humidity) in an environmental chamber for 120 minutes while seated. These conditions simulate a hot summer day in Montreal and are designed to increase skin blood flow through vasodilation, potentially accelerating insulin absorption from subcutaneous depot sites. The combination of heat and humidity will induce thermal stress and sweating responses. Participants will wear standard clothing (shorts and t-shirt) with access to water as needed. The same comprehensive monitoring protocol applies: continuous measurement of core body temperature, skin temperature at four body sites, heart rate, blood pressure every 10 minutes, and blood glucose every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes. The exposure will be terminated if core body temperature reaches ≥39.5°C. Receives: Other: Environmental Temperature Exposure |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in plasma glucose concentration during temperature exposure
The primary outcome is the change in plasma glucose levels (mmol/L) from baseline to end of exposure across the three temperature conditions (cold 10°C, neutral 23°C, hot/humid 36°C). Blood samples will be collected via intravenous catheter and analyzed for plasma glucose concentration. This measure will assess whether ambient temperature affects blood glucose control in individuals with type 1 diabetes, with the hypothesis that cold exposure may increase glucose levels due to slower insulin absorption, while heat exposure may decrease glucose levels due to faster insulin absorption.
Measured: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
Secondary outcomes (5)
Change in plasma insulin concentration during temperature exposure
Change in circulating insulin levels (pmol/L) from baseline across the three temperature conditions. Blood samples collected via intravenous catheter will be analyzed for plasma insulin concentration to assess temperature effects on insulin absorption from subcutaneous injection sites.
Measured: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
24-hour time in glucose range
Percentage of time spent in target glucose range (3.9-10.0 mmol/L) as measured by continuous glucose monitoring (Dexcom G7). This will assess whether temperature exposure has lasting effects on glucose control beyond the immediate exposure period.
Measured: 24 hours before and 24 hours after each temperature exposure visit.
24-hour time above glucose range
Percentage of time spent above target glucose range (>10.0 mmol/L) as measured by continuous glucose monitoring. This measure will identify potential hyperglycemic episodes following temperature exposure.
Measured: 24 hours before and 24 hours after each temperature exposure visit.
24-hour time below glucose range
Percentage of time spent below target glucose range (<3.9 mmol/L) as measured by continuous glucose monitoring. This safety measure will identify potential hypoglycemic episodes following temperature exposure.
Measured: 24 hours before and 24 hours after each temperature exposure visit.
Continuous glucose monitor accuracy
Mean absolute relative difference (MARD) between continuous glucose monitor readings and plasma glucose measurements. This will assess whether temperature conditions affect the accuracy of glucose monitoring technology, which is critical for diabetes management during extreme weather.
Measured: During each 2-hour temperature exposure.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Mar 2026
- Study startMar 2026 (estimated)
- Primary completionMar 2027 (estimated)
- Study completionJul 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (18)Papers the sponsor has linked to this study.
- Other trials for Type 1 Diabetes MellitusStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- This is a randomized crossover study where all 30 participants will experience three temperature conditions (cold 10°C, neutral 23°C, and hot/humid 36°C) in random order. Each participant serves as their own control, completing all three 2-hour environmental chamber exposures separated by at least 3 days. During each visit, participants remain seated while researchers continuously monitor blood glucose, body temperature, heart rate, and blood pressure, with blood samples collected at baseline, 60 minutes, and 120 minutes. The crossover design eliminates individual variability in diabetes management and insulin sensitivity, allowing precise detection of temperature effects on insulin absorption and glucose control.
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institut de Recherches Cliniques de Montreal
- Sponsor type
- University, hospital or other
- Collaborators
- Cardiometabolic Health, Diabetes and Obesity Research Network, Centre EPIC
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07491133
- Sponsor's protocol ID
- 2026-1330
- Acronym
- T1Temp
- Status last verified
- Mar 2026
- First submitted
- 18 Mar 2026
- Last updated
- 24 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Stapleton JM, Yardley JE, Boulay P, Sigal RJ, Kenny GP. Whole-body heat loss during exercise in the heat is not impaired in type 1 diabetes. Med Sci Sports Exerc. 2013 Sep;45(9):1656-64. doi: 10.1249/MSS.0b013e31829002f3.
PubMed 23475170Wolf ST, Havenith G, Kenney WL. Relatively minor influence of individual characteristics on critical wet-bulb globe temperature (WBGT) limits during light activity in young adults (PSU HEAT Project). J Appl Physiol (1985). 2023 May 1;134(5):1216-1223. doi: 10.1152/japplphysiol.00657.2022. Epub 2023 Mar 30.
PubMed 36995912Taylor NA. Human heat adaptation. Compr Physiol. 2014 Jan;4(1):325-65. doi: 10.1002/cphy.c130022.
PubMed 24692142Singh N, Areal AT, Breitner S, Zhang S, Agewall S, Schikowski T, Schneider A. Heat and Cardiovascular Mortality: An Epidemiological Perspective. Circ Res. 2024 Apr 26;134(9):1098-1112. doi: 10.1161/CIRCRESAHA.123.323615. Epub 2024 Apr 25.
PubMed 38662866Robine JM, Cheung SL, Le Roy S, Van Oyen H, Griffiths C, Michel JP, Herrmann FR. Death toll exceeded 70,000 in Europe during the summer of 2003. C R Biol. 2008 Feb;331(2):171-8. doi: 10.1016/j.crvi.2007.12.001. Epub 2007 Dec 31.
PubMed 18241810Ratter-Rieck JM, Roden M, Herder C. Diabetes and climate change: current evidence and implications for people with diabetes, clinicians and policy stakeholders. Diabetologia. 2023 Jun;66(6):1003-1015. doi: 10.1007/s00125-023-05901-y. Epub 2023 Mar 25.
PubMed 36964771Nakaji S, Parodi S, Fontana V, Umeda T, Suzuki K, Sakamoto J, Fukuda S, Wada S, Sugawara K. Seasonal changes in mortality rates from main causes of death in Japan (1970--1999). Eur J Epidemiol. 2004;19(10):905-13. doi: 10.1007/s10654-004-4695-8.
PubMed 15575348Masselot P, Mistry M, Vanoli J, Schneider R, Iungman T, Garcia-Leon D, Ciscar JC, Feyen L, Orru H, Urban A, Breitner S, Huber V, Schneider A, Samoli E, Stafoggia M, de'Donato F, Rao S, Armstrong B, Nieuwenhuijsen M, Vicedo-Cabrera AM, Gasparrini A; MCC Collaborative Research Network; EXHAUSTION project. Excess mortality attributed to heat and cold: a health impact assessment study in 854 cities in Europe. Lancet Planet Health. 2023 Apr;7(4):e271-e281. doi: 10.1016/S2542-5196(23)00023-2. Epub 2023 Mar 16.
PubMed 36934727Information CIfH, 2020. Drug use among seniors in Canada.
Gasparrini A, Guo Y, Sera F, Vicedo-Cabrera AM, Huber V, Tong S, de Sousa Zanotti Stagliorio Coelho M, Nascimento Saldiva PH, Lavigne E, Matus Correa P, Valdes Ortega N, Kan H, Osorio S, Kysely J, Urban A, Jaakkola JJK, Ryti NRI, Pascal M, Goodman PG, Zeka A, Michelozzi P, Scortichini M, Hashizume M, Honda Y, Hurtado-Diaz M, Cesar Cruz J, Seposo X, Kim H, Tobias A, Iniguez C, Forsberg B, Astrom DO, Ragettli MS, Guo YL, Wu CF, Zanobetti A, Schwartz J, Bell ML, Dang TN, Van DD, Heaviside C, Vardoulakis S, Hajat S, Haines A, Armstrong B. Projections of temperature-related excess mortality under climate change scenarios. Lancet Planet Health. 2017 Dec;1(9):e360-e367. doi: 10.1016/S2542-5196(17)30156-0.
PubMed 29276803Gasparrini A, Guo Y, Hashizume M, Lavigne E, Zanobetti A, Schwartz J, Tobias A, Tong S, Rocklov J, Forsberg B, Leone M, De Sario M, Bell ML, Guo YL, Wu CF, Kan H, Yi SM, de Sousa Zanotti Stagliorio Coelho M, Saldiva PH, Honda Y, Kim H, Armstrong B. Mortality risk attributable to high and low ambient temperature: a multicountry observational study. Lancet. 2015 Jul 25;386(9991):369-75. doi: 10.1016/S0140-6736(14)62114-0. Epub 2015 May 20.
PubMed 26003380Gallo E, Quijal-Zamorano M, Mendez Turrubiates RF, Tonne C, Basagana X, Achebak H, Ballester J. Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health. Nat Med. 2024 Nov;30(11):3101-3105. doi: 10.1038/s41591-024-03186-1. Epub 2024 Aug 12.
PubMed 39134730Damiano ER, El-Khatib FH, Zheng H, Nathan DM, Russell SJ. A comparative effectiveness analysis of three continuous glucose monitors. Diabetes Care. 2013 Feb;36(2):251-9. doi: 10.2337/dc12-0070. Epub 2012 Dec 28.
PubMed 23275350Costello A, Abbas M, Allen A, Ball S, Bell S, Bellamy R, Friel S, Groce N, Johnson A, Kett M, Lee M, Levy C, Maslin M, McCoy D, McGuire B, Montgomery H, Napier D, Pagel C, Patel J, de Oliveira JA, Redclift N, Rees H, Rogger D, Scott J, Stephenson J, Twigg J, Wolff J, Patterson C. Managing the health effects of climate change: Lancet and University College London Institute for Global Health Commission. Lancet. 2009 May 16;373(9676):1693-733. doi: 10.1016/S0140-6736(09)60935-1. No abstract available.
PubMed 19447250Carter MR, McGinn R, Barrera-Ramirez J, Sigal RJ, Kenny GP. Impairments in local heat loss in type 1 diabetes during exercise in the heat. Med Sci Sports Exerc. 2014 Dec;46(12):2224-33. doi: 10.1249/MSS.0000000000000350.
PubMed 24784146
Study at a glance
From the registry record, last updated by the sponsor on 24 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Ambient Temperature on Insulin Absorption and Change in Blood Glucose Levels in Individuals With Type 1 Diabetes
- ClinicalTrials.gov ID
- NCT07491133
- Acronym / sponsor ID
- T1Temp / 2026-1330
- Conditions
- Type 1 Diabetes Mellitus
- Keywords
- Type 1 diabetes, Insulin absorption, Temperature exposure, Blood glucose, Continuous glucose monitoring, Hypoglycemia
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Institut de Recherches Cliniques de MontrealUniversity, hospital or other
- Collaborators
- Cardiometabolic Health, Diabetes and Obesity Research Network, Centre EPIC
- Study start
- Mar 2026 (estimated)
- Primary completion
- Mar 2027 (estimated)
- Study completion
- Jul 2027 (estimated)
- First posted
- 24 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to learn how different temperatures affect blood sugar levels in adults with type 1 diabetes. Climate change is causing more extreme hot and cold weather, and people with type 1 diabetes may be at higher risk during these temperature changes. The main questions it aims to answer are:
- Do different temperatures (cold, normal, or hot) change blood sugar levels in people with type 1 diabetes?
- How does temperature affect insulin absorption in the body?
Researchers will compare three different temperature conditions to see how each affects blood sugar levels and insulin in the body.
Participants will:
- Complete a screening visit with body measurements and questionnaires
- Attend 3 separate study visits, each in a different temperature setting:
- Cold room (10°C/50°F)
- Normal room temperature (23°C/73°F)
- Hot and humid room (36°C/97°F with 65% humidity)
- Sit for 2 hours in each temperature condition while researchers monitor their blood sugar, heart rate, and body temperature
- Wear a continuous glucose monitor for 48-72 hours before each visit
- Keep a diary of food, sleep, and activity for 24 hours before and after each visit
Each temperature visit is separated by at least 3 days. The study helps researchers understand if people with type 1 diabetes need special guidance for managing their blood sugar during extreme weather.
Detailed description
Background and Rationale
Climate change is increasing the frequency of extreme weather events, including heat waves and cold snaps. People with type 1 diabetes face higher risks of illness and death during these extreme temperature periods compared to people without diabetes. However, the reasons for this increased risk are not well understood.
When insulin is injected under the skin, it forms a small reservoir from which it gradually enters the bloodstream. Temperature may affect how quickly this insulin is absorbed. Warmer temperatures increase blood flow to the skin, which could speed up insulin absorption and potentially cause blood sugar to drop too low (hypoglycemia). Colder temperatures might slow insulin absorption, leading to higher blood sugar levels (hyperglycemia).
Previous research from the 1980s showed that heating or cooling the injection site affects insulin absorption, but these studies were conducted before modern rapid-acting insulins and diabetes technologies like insulin pumps and continuous glucose monitors were available. No recent studies have examined how whole-body temperature exposure affects insulin absorption and blood sugar control in people with type 1 diabetes.
Study Design Overview
This is a randomized, crossover clinical trial where each participant will experience all three temperature conditions in random order. The study includes:
- 1 preliminary visit for screening and measurements
- 3 experimental visits (cold, neutral, hot conditions)
- Total participation time: approximately 14 hours over up to 4 months
Study Population
The study will enroll 30 adults aged 18-45 years with type 1 diabetes for at least 2 years. Participants will be equally divided by:
- Sex: 50% male, 50% female
- Insulin delivery method: 10 using multiple daily injections, 10 using insulin pumps, 10 using hybrid closed-loop systems
Preliminary Visit Procedures
During the first visit at the Montreal Clinical Research Institute (IRCM), participants will:
- Review and sign informed consent documents
- Complete medical history and lifestyle questionnaires
- Fill out a heat exposure questionnaire based on Health Canada guidelines
- Complete the GENESIS PRAXY questionnaire to document gender-related factors
- Undergo body measurements including height, weight, waist circumference, and body composition scan
- Have resting heart rate and blood pressure measured
- Receive training on continuous glucose monitor use (if not already using one)
Experimental Visit Procedures
Each of the three experimental visits will take place at Centre ÉPIC and follow the same protocol in different temperature conditions:
Pre-Exposure Phase (60 minutes)
- Participants arrive 2 hours after eating a standardized snack (100g Greek yogurt) with their usual insulin dose
- Body weight measurement
- Installation of rectal temperature probe (self-inserted privately)
- Placement of intravenous catheter for blood sampling
- Attachment of skin temperature sensors, blood pressure cuff, and heart rate monitor
- 60-minute rest period at room temperature to establish baseline measurements
Temperature Exposure Phase (120 minutes)
Participants will sit in an environmental chamber set to one of three conditions:
- Cold: 10°C (50°F) - causes shivering and increases energy expenditure by approximately 80%
- Neutral: 23°C (73°F) - comfortable room temperature
- Hot/Humid: 36°C (97°F) with 65% humidity - simulates a hot summer day in Montreal
Measurements During Exposure
Continuous monitoring:
- Heart rate via chest strap monitor
- Core body temperature via rectal probe
- Skin temperature at four sites (arm, chest, thigh, calf)
- Blood sugar levels via continuous glucose monitor (checked every 15 minutes)
Intermittent measurements:
- Blood pressure every 10 minutes
- Blood samples at baseline, 60 minutes, and 120 minutes for analysis of glucose, insulin, glucagon, and other metabolic markers
- Comfort and sensation ratings every 10 minutes using visual scales for thermal comfort, thermal sensation, and thirst
Safety Monitoring
Throughout each visit, research staff will continuously monitor participants for:
- Signs of hypoglycemia (low blood sugar) - treated immediately with glucose if needed
- Core body temperature limits (stopped if ≤35.5°C during cold or ≥39.5°C during heat exposure)
- Blood pressure limits (stopped if >180/110 mmHg or <90/60 mmHg)
- Participant comfort and willingness to continue
Data Collection
24-Hour Activity Logs
Participants will record their food intake, insulin doses, sleep patterns, and physical activity for:
- 48 hours before the preliminary visit (baseline lifestyle)
- 24 hours before each experimental visit
- 24 hours after each experimental visit
Continuous Glucose Monitoring
A Dexcom G7 sensor will be installed 48-72 hours before each visit to capture:
- Glucose patterns during temperature exposure
- 24-hour glucose control before and after each visit
- Time spent in target range (3.9-10.0 mmol/L)
- Time spent above target (>10.0 mmol/L)
- Time spent below target (<3.9 mmol/L)
Laboratory Analyses
Blood samples will be analyzed for:
- Plasma glucose and insulin levels
- Glucagon (hormone that raises blood sugar)
- Free fatty acids and glycerol (markers of fat metabolism)
- Other metabolic hormones
Special Considerations
For Female Participants Study visits will be scheduled during the follicular phase of the menstrual cycle (or placebo pill phase for those using oral contraceptives) since hormonal changes can affect blood sugar levels.
Insulin Delivery Methods The study will examine whether different insulin delivery methods (injections, pumps, or automated systems) respond differently to temperature changes.
Participant Safety and Comfort
- At least two research staff members will be present during each visit
- One staff member will remain in the environmental chamber with the participant
- Participants can request to stop the exposure at any time
- Emergency procedures are in place for severe blood sugar episodes
- Socks and gloves will be provided during cold exposure if needed
Study Significance
This research will provide the first modern evidence about how environmental temperature affects insulin absorption and blood sugar control in people with type 1 diabetes. The findings could lead to new clinical guidelines for diabetes management during extreme weather events, potentially reducing the increased health risks that people with type 1 diabetes face during heat waves and cold snaps.
The study results may inform recommendations for insulin dose adjustments during temperature extremes and help health care providers better advise patients with type 1 diabetes about managing their condition during increasingly frequent extreme weather events related to climate change.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- This is a randomized crossover study where all 30 participants will experience three temperature conditions (cold 10°C, neutral 23°C, and hot/humid 36°C) in random order. Each participant serves as their own control, completing all three 2-hour environmental chamber exposures separated by at least 3 days. During each visit, participants remain seated while researchers continuously monitor blood glucose, body temperature, heart rate, and blood pressure, with blood samples collected at baseline, 60 minutes, and 120 minutes. The crossover design eliminates individual variability in diabetes management and insulin sensitivity, allowing precise detection of temperature effects on insulin absorption and glucose control.
| Arm | Type | Receives |
|---|---|---|
| Cold exposure | Experimental | Other: Environmental Temperature ExposureParticipants will be exposed to cold temperature (10°C/50°F) in an environmental chamber for 120 minutes while seated. This temperature is designed to induce shivering thermogenesis and increase energy expenditure by approximately 80%. The cold exposure may slow insulin absorption from subcutaneous injection sites due to reduced skin blood flow and vasoconstriction. Participants will wear standard clothing (shorts and t-shirt) with optional socks and gloves if needed for comfort. Continuous monitoring includes core body temperature via rectal probe, skin temperature at four sites, heart rate, blood pressure every 10 minutes, and blood glucose via continuous glucose monitor every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes for plasma glucose, insulin, glucagon, and metabolic markers. The exposure will be terminated if core body temperature drops to ≤35.5°C. |
| Neutral Temperature | Active comparator | Other: Environmental Temperature ExposureParticipants will be exposed to neutral room temperature (23°C/73°F) in an environmental chamber for 120 minutes while seated. This condition serves as the control/reference temperature representing typical indoor environmental conditions. At this temperature, normal thermoregulatory responses are minimal, allowing assessment of baseline insulin absorption and glucose responses without temperature-induced physiological stress. Participants will wear standard clothing (shorts and t-shirt) and undergo the same monitoring protocol as other arms: continuous core and skin temperature measurement, heart rate monitoring, blood pressure every 10 minutes, blood glucose monitoring every 15 minutes via continuous glucose monitor, and blood sampling at baseline, 60 minutes, and 120 minutes. |
| Hot/Humid Exposure | Experimental | Other: Environmental Temperature ExposureParticipants will be exposed to hot and humid conditions (36°C/97°F with 65% relative humidity) in an environmental chamber for 120 minutes while seated. These conditions simulate a hot summer day in Montreal and are designed to increase skin blood flow through vasodilation, potentially accelerating insulin absorption from subcutaneous depot sites. The combination of heat and humidity will induce thermal stress and sweating responses. Participants will wear standard clothing (shorts and t-shirt) with access to water as needed. The same comprehensive monitoring protocol applies: continuous measurement of core body temperature, skin temperature at four body sites, heart rate, blood pressure every 10 minutes, and blood glucose every 15 minutes. Blood samples will be collected at baseline, 60 minutes, and 120 minutes. The exposure will be terminated if core body temperature reaches ≥39.5°C. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Diagnosis of type 1 diabetes for more than 2 years
- Ability to provide verbal and written informed consent
- Ability to speak and understand French
Key exclusion criteria (6 listed)
- Recent and/or unstable health condition (less than 3 months) prior to enrolment
- Any viral infection at time of participation
- Chronic illness other than type 1 diabetes (for example: pulmonary disease, cardiovascular disease, cancer)
- Health condition not controlled by medication
- Pregnancy or breastfeeding (for female participants)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Environmental Temperature ExposureAlso: Temperature Stress Testing, Thermal Exposure Protocol, Environmental Chamber Study, Ambient Temperature InterventionSystematic exposure to controlled temperature and humidity conditions in a specialized environmental chamber. Each exposure lasts 120 minutes with participants remaining seated throughout. All exposures include standardized pre-exposure preparation (60-minute baseline period at room temperature), continuous physiological monitoring, standardized clothing, and identical blood sampling schedules. Safety protocols include continuous staff supervision, predetermined stopping criteria for extreme body temperatures or blood pressure changes, and immediate availability of warming/cooling interventions and hypoglycemia treatment protocols. | Other | Cold exposure, Hot/Humid Exposure, Neutral Temperature |
Primary outcome
Change in plasma glucose concentration during temperature exposure
Time frame: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
The primary outcome is the change in plasma glucose levels (mmol/L) from baseline to end of exposure across the three temperature conditions (cold 10°C, neutral 23°C, hot/humid 36°C). Blood samples will be collected via intravenous catheter and analyzed for plasma glucose concentration. This measure will assess whether ambient temperature affects blood glucose control in individuals with type 1 diabetes, with the hypothesis that cold exposure may increase glucose levels due to slower insulin absorption, while heat exposure may decrease glucose levels due to faster insulin absorption.
5 secondary outcomes
Change in plasma insulin concentration during temperature exposure
Time frame: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.
24-hour time in glucose range
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
24-hour time above glucose range
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
24-hour time below glucose range
Time frame: 24 hours before and 24 hours after each temperature exposure visit.
Continuous glucose monitor accuracy
Time frame: During each 2-hour temperature exposure.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Mar 2026.
- Background: PubMed 23475170Stapleton JM, Yardley JE, Boulay P, Sigal RJ, Kenny GP. Whole-body heat loss during exercise in the heat is not impaired in type 1 diabetes. Med Sci Sports Exerc. 2013 Sep;45(9):1656-64. doi: 10.1249/MSS.0b013e31829002f3.
- Background: PubMed 36995912Wolf ST, Havenith G, Kenney WL. Relatively minor influence of individual characteristics on critical wet-bulb globe temperature (WBGT) limits during light activity in young adults (PSU HEAT Project). J Appl Physiol (1985). 2023 May 1;134(5):1216-1223. doi: 10.1152/japplphysiol.00657.2022. Epub 2023 Mar 30.
- Background: PubMed 24692142Taylor NA. Human heat adaptation. Compr Physiol. 2014 Jan;4(1):325-65. doi: 10.1002/cphy.c130022.
- Background: PubMed 38662866Singh N, Areal AT, Breitner S, Zhang S, Agewall S, Schikowski T, Schneider A. Heat and Cardiovascular Mortality: An Epidemiological Perspective. Circ Res. 2024 Apr 26;134(9):1098-1112. doi: 10.1161/CIRCRESAHA.123.323615. Epub 2024 Apr 25.
- Background: PubMed 18241810Robine JM, Cheung SL, Le Roy S, Van Oyen H, Griffiths C, Michel JP, Herrmann FR. Death toll exceeded 70,000 in Europe during the summer of 2003. C R Biol. 2008 Feb;331(2):171-8. doi: 10.1016/j.crvi.2007.12.001. Epub 2007 Dec 31.
- Background: PubMed 36964771Ratter-Rieck JM, Roden M, Herder C. Diabetes and climate change: current evidence and implications for people with diabetes, clinicians and policy stakeholders. Diabetologia. 2023 Jun;66(6):1003-1015. doi: 10.1007/s00125-023-05901-y. Epub 2023 Mar 25.
- Background: PubMed 15575348Nakaji S, Parodi S, Fontana V, Umeda T, Suzuki K, Sakamoto J, Fukuda S, Wada S, Sugawara K. Seasonal changes in mortality rates from main causes of death in Japan (1970--1999). Eur J Epidemiol. 2004;19(10):905-13. doi: 10.1007/s10654-004-4695-8.
- Background: PubMed 36934727Masselot P, Mistry M, Vanoli J, Schneider R, Iungman T, Garcia-Leon D, Ciscar JC, Feyen L, Orru H, Urban A, Breitner S, Huber V, Schneider A, Samoli E, Stafoggia M, de'Donato F, Rao S, Armstrong B, Nieuwenhuijsen M, Vicedo-Cabrera AM, Gasparrini A; MCC Collaborative Research Network; EXHAUSTION project. Excess mortality attributed to heat and cold: a health impact assessment study in 854 cities in Europe. Lancet Planet Health. 2023 Apr;7(4):e271-e281. doi: 10.1016/S2542-5196(23)00023-2. Epub 2023 Mar 16.
- BackgroundInformation CIfH, 2020. Drug use among seniors in Canada.
- Background: PubMed 29276803Gasparrini A, Guo Y, Sera F, Vicedo-Cabrera AM, Huber V, Tong S, de Sousa Zanotti Stagliorio Coelho M, Nascimento Saldiva PH, Lavigne E, Matus Correa P, Valdes Ortega N, Kan H, Osorio S, Kysely J, Urban A, Jaakkola JJK, Ryti NRI, Pascal M, Goodman PG, Zeka A, Michelozzi P, Scortichini M, Hashizume M, Honda Y, Hurtado-Diaz M, Cesar Cruz J, Seposo X, Kim H, Tobias A, Iniguez C, Forsberg B, Astrom DO, Ragettli MS, Guo YL, Wu CF, Zanobetti A, Schwartz J, Bell ML, Dang TN, Van DD, Heaviside C, Vardoulakis S, Hajat S, Haines A, Armstrong B. Projections of temperature-related excess mortality under climate change scenarios. Lancet Planet Health. 2017 Dec;1(9):e360-e367. doi: 10.1016/S2542-5196(17)30156-0.
- Background: PubMed 26003380Gasparrini A, Guo Y, Hashizume M, Lavigne E, Zanobetti A, Schwartz J, Tobias A, Tong S, Rocklov J, Forsberg B, Leone M, De Sario M, Bell ML, Guo YL, Wu CF, Kan H, Yi SM, de Sousa Zanotti Stagliorio Coelho M, Saldiva PH, Honda Y, Kim H, Armstrong B. Mortality risk attributable to high and low ambient temperature: a multicountry observational study. Lancet. 2015 Jul 25;386(9991):369-75. doi: 10.1016/S0140-6736(14)62114-0. Epub 2015 May 20.
- Background: PubMed 39134730Gallo E, Quijal-Zamorano M, Mendez Turrubiates RF, Tonne C, Basagana X, Achebak H, Ballester J. Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health. Nat Med. 2024 Nov;30(11):3101-3105. doi: 10.1038/s41591-024-03186-1. Epub 2024 Aug 12.
- Individual participant dataSharing planned: No
Related trials for Type 1 Diabetes Mellitus
Not yet recruitingPhase 3
A Study to Evaluate the Effectiveness and Safety of the Drug AZD6234 for Managing Weight in Adults Who Are Obese or Overweight. These Participants May or May Not Also Have Type 2 Diabetes
Obesity, Overweight
RecruitingPhase 1
Pharmacokinetics, Safety, and Immunogenicity Comparison of Bmab1700 and Opdivo® as Adjuvant Monotherapy in Participants With Melanoma
Melanoma
Active, not recruitingPhase 2
A Study of Botensilimab and Balstilimab for the Treatment of Colorectal Cancer
Metastatic Colorectal Cancer
Not yet recruiting
Inter-Arm Differences in Continuous Glucose Monitor Readings in Adults With Diabetes
Continuous Glucose Monitoring, Type 1 Diabetes
RecruitingObservational study
Estimated Risk of Preeclampsia in the First Trimester and Its Association With Subclinical Atherosclerosis and Cardiovascular Risk in Women With Type 1 Diabetes
Type 1 Diabetes, Preeclampsia
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Environmental Temperature Exposure in people with Type 1 Diabetes Mellitus, run by Institut de Recherches Cliniques de Montreal at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 24 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Corinne Suppere, MSc (514-987-5597, corinne.suppere@ircm.qc.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in plasma glucose concentration during temperature exposure (time frame: Measured at baseline, 60 minutes, and 120 minutes during each 2-hour environmental chamber exposure.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07491133, which also lists 18 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Mar 2026.