HypertensionNCT00837122
Genetics of Type 2 Diabetes in West Africans
An observational study of Hypertension and Diabetes, run by National Human Genome Research Institute (NHGRI) at 5 sites in 2 countries.
Trial summary
Background: Type 2 diabetes (T2D) and associated complications are major contributors to the global disease burden. T2D is already a major health threat in populations in developed countries and is rapidly taking hold in the developing world. Read more about this study
- Who is it for?
- Ages 18 to 120 yearsHealthy volunteers can take part
- Conditions the study is for
- Hypertension, Diabetes
- How many people
- 10,000 participants
- Where
- 5 sitesin 2 countries
- Study dates
- 3 Feb 2009to not given
- Phase
- Observational
- 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 120 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Patients with confirmed T2D who are newly diagnosed or on treatment and those without T2D (ethnically matched) in Ibadan, Nigeria
Who may be able to join
- As our primary interest is in T2D, it is important to exclude individuals who may have diabetes of another etiology. Elevated blood glucose in individuals 25 years old or younger is unlikely (in West Africa) to result from T2D and may reflect Type 1 Diabetes. Therefore, only individuals older than 25 years will be included in this study.
- We are seeking to enroll persons without T2D or with previously or newly diagnosed T2D. Previously diagnosed cases will be determined by self-report of being treated with oral medication or insulin. Newly diagnosed cases will be determined by fasting blood glucose value >= 126 mg/dl on more than one occasion. Individuals who have elevated blood glucose during their initial reading will be asked to return to the study site for a second test. If this test also has a fasting blood glucose value >= 126 mg/dl, then they will be considered a new case. The control group will be individuals with no report of T2D diagnosis and fasting plasma glucose (FPG)< 126 mg/dl.
- Only unrelated individuals will be included in this phase of the study to avoid confounding genetic association studies by relatedness in the study population.
Who cannot join
- An individual who meets any of the following criteria will be excluded from participation in this study:
- Incarceration.
- Lack capacity to consent to research participation.
- Pregnancy.
Trial locations and contacts
5 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
5 sites in 2 countries
Nigeria3 sites, 1 recruiting
- Completed
University of Nigeria
Enugu
- Recruiting
University of Ibadan
Ibadan
Clement Adebamowo, M.D., (410) 706-6116, cadebamo@yahoo.com
- Completed
University of Lagos
Lagos
Ghana2 sites
- Completed
University of Ghana
Accra
- Completed
University of Science and Tech
Kumasi
About this study
Official title: Genetics of Type 2 Diabetes in Diverse Populations
Background:
- Type 2 diabetes (T2D) and associated complications are major contributors to the global disease burden. T2D is already a major health threat in populations in developed countries and is rapidly taking hold in the developing world.
- It is believed that understanding the complex interplay between genetic and lifestyle characteristics in the etiology of T2D and related complications will lead to the development of better preventive and therapeutic strategies. In Addition, the results of this project will facilitate our understanding of causes of diabetes in African Americans, other US and world populations
Read more
Objectives:
- To conduct a genome-wide association study (GWAS) to identify susceptibility genetic variants for diabetes among the Yoruba people in Ibadan, Nigeria.
- To enroll and examine 300 unrelated cases of T2D and 300 ethnicity-matched Yoruba controls.
- To conduct resequencing of positional candidate gene/loci to identify likely functional variants in a subset of the cohort.
- To conduct replication studies of the top-100 scoring variants in three independent African and European ancestry samples.
- To investigate whether diabetes-associated variants discovered in European populations increase diabetes risk in West Africans.
Eligibility:
- Patients 18 years of age with confirmed T2D who are newly diagnosed or on treatment of Yoruba ethnicity in Ibadan, Nigeria. Control subjects are nondiabetics ethnically matched to patients.
Design:
- The study design for both patients and controls consists of the following steps:
- Discuss informed consent process and obtain signed informed consent form. Informed consent will be administered by trained clinic staff.
- Assign study ID (barcode)
- Administer questionnaires
- Obtain spot urine sample
- Measure blood pressure
- Obtain anthropometric measurements including body composition
- Perform finger prick for blood glucose level
- Obtain venous blood samples
- Perform eye examination
- On the following day, perform confirmatory blood glucose for the small subset of participants requiring confirmation of previous test result DNA extraction of stored samples will be done at either the National Institutes of Health or the laboratory in Nigeria.
- GWAS will be conducted using publicly available software packages.
Read the detailed description
Study Description:
This protocol is designed to study the genetic basis of Type 2 Diabetes (T2D) and related conditions in Africa.
Objectives:
Primary Objective: To conduct genetic association studies of T2D, T2D complications, and related traits in Africans of diverse ethnic groups
Secondary Objectives:
- To investigate the contribution of gene x environment interactions in T2D risk and in influencing related traits
- To develop a large-scale genetic epidemiological resource for the replication of findings in other studies of related traits
- To conduct trans-ethnic fine-mapping
- To describe the study population epidemiologically in terms of cardiometabolic traits and prevalence of related conditions
- To conduct population genetic analyses to describe population history and to develop statistical techniques appropriate for genetic analyses of African ancestry individuals
- To conduct deep phenotyping to facilitate additional research questions related to cardiometabolic traits and for follow-up previous findings
Endpoints:
Primary Endpoint: T2D
Secondary Endpoints: T2D Complications, Hypertension, Obesity, Dyslipidemia, Metabolic Syndrome, Chronic Kidney Disease, and other cardiometabolic traits
- Conditions
- Hypertension, Diabetes
- Keywords
- African, Natural History
- Medical subject headings
- Hypertension, Diabetes Mellitus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Control | Control subjects are nondiabetics ethnically matched to patients | |
| T2D | Patients with confirmed T2D who are newly diagnosed or on treatment in Ibadan, Nigeria |
What is being measured
The primary outcome is the main question the study is designed to answer.
I
In a subset of participants, to investigate the relationship between diets, gut microbiota, and T2D/related traits.
Measured: ongoing
H
To investigate whether hemoglobin A1c (HbA1c) as an indicator of blood glucose control over time is reliable in the presence of the sickle cell trait (HbS), a common hemoglobinopathy in West Africa. The association between HbA1c repeated measures and changes in T2D-related traits over time will be evaluated. We will also evaluate if there is a systematic difference (bias) in the estimation of A1c in carriers of the sickle trait and non-carriers in persons with and without diabetes.
Measured: ongoing
G
g- In a subset of participants, to investigate key tissues in the pathophysiology of T2D, we will study differences in the gene expression of skeletal muscle and adipose tissue in lean and obese individuals with and without T2D (n=100, Biopsy Substudy).
Measured: ongoing
F
f- To conduct population genetic analyses to describe population history and to develop statistical techniques appropriate for genetic analysis of African ancestry individuals.
Measured: ongoing
E
e-To describe these individuals epidemiologically in terms of metabolic traits and the prevalence of relevant conditions, as, for some traits, this may be the first large-scale epidemiological, population-based study of Africans with the appropriate data for such description.
Measured: ongoing
D
d- To conduct trans-ethnic fine mapping to determine whether the reduced LD across the genome in African ancestry individuals can refine the region of interest around genetic associations discovered in populations of non-African ancestry. To conduct candidate gene resequencing, Whole Genome Sequencing (WGS), or Whole Exome Sequencing (WES), as funding allows, in participants with metabolic profiles of interest. For instance, individuals will be selected who have extreme values for serum lipids for WES. Variants identified by this resequencing will be genotyped in the larger study population for association analysis.
Measured: ongoing
C
c- To develop a large-scale genetic epidemiological resource for the replication of findings in other studies of related traits in African ancestry and non-African ancestry individuals.
Measured: ongoing
B
b- To investigate the contribution of gene x environment interactions in T2D risk and in influencing related traits. These investigations may be conducted on either a hypothesis-driven, locus-specific manner or agnostically, i.e. genome-wide. Environmental variants to be considered include lifestyle factors (e.g. diet, measured by food frequency questionnaires (FFQ), socioeconomic measures, and medications taken.
Measured: ongoing
A
a- To conduct genetic association studies of T2D and related traits (including blood pressure, serum lipids, blood glucose, adiposity) in West Africans of diverse ethnic groups. Approaches will include genome-wide association studies (including exome chip data) and candidate gene/loci association analyses.
Measured: ongoing
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Feb 2009 (estimated)
- Study start3 Feb 2009
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HypertensionStudies 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 10,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- National Human Genome Research Institute (NHGRI)
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
- Investigators
- Charles N Rotimi, M.D., Principal investigator, National Human Genome Research Institute (NHGRI)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00837122
- Sponsor's protocol ID
- 999909070
- Other IDs
- 09-HG-N070
- Status last verified
- 30 Oct 2026
- First submitted
- 4 Feb 2009
- Last updated
- 3 Nov 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Extensive review of the consents related to this protocol by the NHGRI IRB was conducted and it was determined that because the initial consent process did not address sharing of participants' data and the related risks and the carefully established rapport and trust with African populations and collaborators, it would not be appropriate to share participant's data. A memorandum to this effect can be provided, if necessary. We will continue to be open to making the data available through collaboration, a use of the data that was described in initial consent forms.
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Genetics of Type 2 Diabetes in Diverse Populations
- ClinicalTrials.gov ID
- NCT00837122
- Acronym / sponsor ID
- 999909070
- Conditions
- Hypertension, Diabetes
- Keywords
- African, Natural History
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 10,000 participants (estimated)
- Lead sponsor
- National Human Genome Research Institute (NHGRI)US National Institutes of Health
- Study start
- 3 Feb 2009 (actual)
- First posted
- 5 Feb 2009 (estimated)
- 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.
Background:
- Type 2 diabetes (T2D) and associated complications are major contributors to the global disease burden. T2D is already a major health threat in populations in developed countries and is rapidly taking hold in the developing world.
- It is believed that understanding the complex interplay between genetic and lifestyle characteristics in the etiology of T2D and related complications will lead to the development of better preventive and therapeutic strategies. In Addition, the results of this project will facilitate our understanding of causes of diabetes in African Americans, other US and world populations
Objectives:
- To conduct a genome-wide association study (GWAS) to identify susceptibility genetic variants for diabetes among the Yoruba people in Ibadan, Nigeria.
- To enroll and examine 300 unrelated cases of T2D and 300 ethnicity-matched Yoruba controls.
- To conduct resequencing of positional candidate gene/loci to identify likely functional variants in a subset of the cohort.
- To conduct replication studies of the top-100 scoring variants in three independent African and European ancestry samples.
- To investigate whether diabetes-associated variants discovered in European populations increase diabetes risk in West Africans.
Eligibility:
- Patients 18 years of age with confirmed T2D who are newly diagnosed or on treatment of Yoruba ethnicity in Ibadan, Nigeria. Control subjects are nondiabetics ethnically matched to patients.
Design:
- The study design for both patients and controls consists of the following steps:
- Discuss informed consent process and obtain signed informed consent form. Informed consent will be administered by trained clinic staff.
- Assign study ID (barcode)
- Administer questionnaires
- Obtain spot urine sample
- Measure blood pressure
- Obtain anthropometric measurements including body composition
- Perform finger prick for blood glucose level
- Obtain venous blood samples
- Perform eye examination
- On the following day, perform confirmatory blood glucose for the small subset of participants requiring confirmation of previous test result DNA extraction of stored samples will be done at either the National Institutes of Health or the laboratory in Nigeria.
- GWAS will be conducted using publicly available software packages.
Detailed description
Study Description:
This protocol is designed to study the genetic basis of Type 2 Diabetes (T2D) and related conditions in Africa.
Objectives:
Primary Objective: To conduct genetic association studies of T2D, T2D complications, and related traits in Africans of diverse ethnic groups
Secondary Objectives:
- To investigate the contribution of gene x environment interactions in T2D risk and in influencing related traits
- To develop a large-scale genetic epidemiological resource for the replication of findings in other studies of related traits
- To conduct trans-ethnic fine-mapping
- To describe the study population epidemiologically in terms of cardiometabolic traits and prevalence of related conditions
- To conduct population genetic analyses to describe population history and to develop statistical techniques appropriate for genetic analyses of African ancestry individuals
- To conduct deep phenotyping to facilitate additional research questions related to cardiometabolic traits and for follow-up previous findings
Endpoints:
Primary Endpoint: T2D
Secondary Endpoints: T2D Complications, Hypertension, Obesity, Dyslipidemia, Metabolic Syndrome, Chronic Kidney Disease, and other cardiometabolic traits
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Control | – | –Control subjects are nondiabetics ethnically matched to patients |
| T2D | – | –Patients with confirmed T2D who are newly diagnosed or on treatment in Ibadan, Nigeria |
Who may qualify
- Ages
- 18 to 120 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Patients with confirmed T2D who are newly diagnosed or on treatment and those without T2D (ethnically matched) in Ibadan, Nigeria
Key inclusion criteria (3 listed)
- As our primary interest is in T2D, it is important to exclude individuals who may have diabetes of another etiology. Elevated blood glucose in individuals 25 years old or younger is unlikely (in West Africa) to result from T2D and may reflect Type 1 Diabetes. Therefore, only individuals older than 25 years will be included in this study.
- We are seeking to enroll persons without T2D or with previously or newly diagnosed T2D. Previously diagnosed cases will be determined by self-report of being treated with oral medication or insulin. Newly diagnosed cases will be determined by fasting blood glucose value >= 126 mg/dl on more than one occasion. Individuals who have elevated blood glucose during their initial reading will be asked to return to the study site for a second test. If this test also has a fasting blood glucose value >= 126 mg/dl, then they will be considered a new case. The control group will be individuals with no report of T2D diagnosis and fasting plasma glucose (FPG)< 126 mg/dl.
- Only unrelated individuals will be included in this phase of the study to avoid confounding genetic association studies by relatedness in the study population.
Key exclusion criteria (4 listed)
- An individual who meets any of the following criteria will be excluded from participation in this study:
- Incarceration.
- Lack capacity to consent to research participation.
- Pregnancy.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
I
Time frame: ongoing
In a subset of participants, to investigate the relationship between diets, gut microbiota, and T2D/related traits.
H
Time frame: ongoing
To investigate whether hemoglobin A1c (HbA1c) as an indicator of blood glucose control over time is reliable in the presence of the sickle cell trait (HbS), a common hemoglobinopathy in West Africa. The association between HbA1c repeated measures and changes in T2D-related traits over time will be evaluated. We will also evaluate if there is a systematic difference (bias) in the estimation of A1c in carriers of the sickle trait and non-carriers in persons with and without diabetes.
G
Time frame: ongoing
g- In a subset of participants, to investigate key tissues in the pathophysiology of T2D, we will study differences in the gene expression of skeletal muscle and adipose tissue in lean and obese individuals with and without T2D (n=100, Biopsy Substudy).
F
Time frame: ongoing
f- To conduct population genetic analyses to describe population history and to develop statistical techniques appropriate for genetic analysis of African ancestry individuals.
E
Time frame: ongoing
e-To describe these individuals epidemiologically in terms of metabolic traits and the prevalence of relevant conditions, as, for some traits, this may be the first large-scale epidemiological, population-based study of Africans with the appropriate data for such description.
D
Time frame: ongoing
d- To conduct trans-ethnic fine mapping to determine whether the reduced LD across the genome in African ancestry individuals can refine the region of interest around genetic associations discovered in populations of non-African ancestry. To conduct candidate gene resequencing, Whole Genome Sequencing (WGS), or Whole Exome Sequencing (WES), as funding allows, in participants with metabolic profiles of interest. For instance, individuals will be selected who have extreme values for serum lipids for WES. Variants identified by this resequencing will be genotyped in the larger study population for association analysis.
C
Time frame: ongoing
c- To develop a large-scale genetic epidemiological resource for the replication of findings in other studies of related traits in African ancestry and non-African ancestry individuals.
B
Time frame: ongoing
b- To investigate the contribution of gene x environment interactions in T2D risk and in influencing related traits. These investigations may be conducted on either a hypothesis-driven, locus-specific manner or agnostically, i.e. genome-wide. Environmental variants to be considered include lifestyle factors (e.g. diet, measured by food frequency questionnaires (FFQ), socioeconomic measures, and medications taken.
A
Time frame: ongoing
a- To conduct genetic association studies of T2D and related traits (including blood pressure, serum lipids, blood glucose, adiposity) in West Africans of diverse ethnic groups. Approaches will include genome-wide association studies (including exome chip data) and candidate gene/loci association analyses.
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 3 Nov 2026.
- Individual participant dataSharing planned: No. Extensive review of the consents related to this protocol by the NHGRI IRB was conducted and it was determined that because the initial consent process did not address sharing of participants' data and the related risks and the carefully established rapport and trust with African populations and collaborators, it would not be appropriate to share participant's data. A memorandum to this effect can be provided, if necessary. We will continue to be open to making the data available through collaboration, a use of the data that was described in initial consent forms.
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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.
Charles N Rotimi, M.D. principal investigator
National Human Genome Research Institute (NHGRI)
5 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Hypertension and Diabetes, run by National Human Genome Research Institute (NHGRI) at 5 sites in 2 countries.
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 4 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: looking for participants now, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 5 sites in Nigeria, Ghana. 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 Shirley T Freeman ((301) 451-2302, freemansh@mail.nih.gov), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
I (time frame: ongoing). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 3 Nov 2026.