Sleep Patterns and Chronotype in Children With and Without Type 1 Diabetes

Type 1 diabetes (T1D) is one of the most common chronic diseases in childhood. The prevalence of T1D in Turkey is reported to be 0.75%. Recent studies draw attention to the close relationship between type 1 diabetes and sleep problems. It has been suggested that sleep duration is insufficient and sleep quality is impaired in patients with T1D. Sleep problems have been reported to include sleep onset, sleep maintenance, frequent nighttime awakenings, and daytime sleepiness. Conditions such as nocturnal glycemic variability and fear of hypoglycemia specific to patients with T1D, alarms from devices such as continuous glucose monitors and pumps used in diabetes management, anxiety, stress and depressive symptoms associated with diabetes, and treatment that may sometimes last throughout the night are possible factors that adversely affect the sleep health of people with diabetes. Studies show that children with T1D sleep significantly less than their peers without diabetes and that this is associated with poorer glycemic control in type 1 diabetes due to impaired glucose metabolism. The American Diabetes Association (ADA) has emphasized that sleep health should be included in the routine assessment of people with diabetes by 2022.

This study aimed to compare sleep health composite dimensions and chronotype in children and adolescents with and without T1D, and to explore the relationship between sleep and glycemic variability in T1D.

The study was designed as a prospective observational case-control study. The estimated sample size is calculated as 168.

The sleep health composite dimensions were measured using actigraphy, sleep diaries, and self- or parental reports. This composite evaluates various dimensions of sleep, including regularity, satisfaction, alertness, timing, efficiency, and duration. Each dimension is assigned a code of '1' for 'good' and '0' for 'poor.' The sleep health composite is designed so that a higher score indicates better overall sleep health.

Sleep disturbances were assessed using the DSM-5 Level 2-Sleep Disturbance Scale Short Form. The DSM-5 Level 2-Sleep Disorders Scale short form was used to evaluate sleep disturbances. It is an 8-item scale that specifically evaluates sleep disorders in children and adolescents, within the past 7 days. Each item is rated on a 5-point scale (1=never; 2=rarely; 3=sometimes; 4=often, and 5=always). The total score ranges from 8 to 40 points, with higher scores indicating more severe sleep disturbances. Sleep/wake patterns were also assessed using sleep diaries.

The Childhood Chronotype Questionnaire was used to evaluate the chronotype in children. This 27-item questionnaire was developed for Turkish children in the light of the Munich Chronotype Questionnaire and the Mornings-Evenings Questionnaire. The chronotypes were classified as morning, intermediate and evening types, corresponding scores of ≤23, 24-32 and ≥33. The child form of the Childhood Chronotype Questionnaire was completed by the parent and the adolescent form was completed by the adolescent.

Glycemic variability was assessed using continuous glucose monitoring (CGM) device parameters. Glycemic variability was evaluated using the J index to assess the effectiveness of glycemic control (calculated as 0.001 × (mean + SD)), the low blood glucose index (LBGI) to evaluate the risk of hypoglycemia, the high blood glucose index (HBGI) to determine the likelihood of hyperglycemia, and the Coefficient of Variation (CV). The Coefficient of Variation expresses the percentage variation in blood glucose levels, with a CV ≤36% indicating a stable glucose profile and a CV >36% indicating an unstable glucose profile. For 24-hour continuous glucose monitoring, the targeted percentages of time were >70% at 70-180 mg/dl for glycemic control, <4% at <70 mg/dl for hypoglycemia, <1% at <54 mg/dl for severe hypoglycemia, <25% at >180 mg/dl for hyperglycemia and <5% at >250 mg/dl for severe hyperglycemia. The hemoglobin A1c level is also used for glycemic control.