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Little is known about the pathophysiology of diabetes in Africans. Thus, we assessed whether insulin resistance and beta-cell function differed by ethnicity in Kenya and whether differences were modified by abdominal fat distribution. A cross-sectional study in 1,087 rural Luo (n = 361), Kamba (n = 378), and Maasai (n = 348) was conducted. All participants had a standard 75-g oral glucose tolerance test (OGTT). Venous blood samples were collected at 0, 30, and 120 min. Serum insulin was analysed at 0 and 30 min. From the OGTT, we assessed the homoeostasis model assessment of insulin resistance by computer model, early phase insulin secretion, and disposition index (DI) dividing insulin secretion by insulin resistance. Abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) thickness were carried out by ultrasonography. Linear regression analyses were done to assess ethnic differences in insulin indices. The Maasai had 32 and 17% higher insulin resistance than the Luo and Kamba, respectively (p < 0.001). Early phase insulin secretion was 16% higher in the Maasai compared to the Luo (p < 0.001). DI was 12% (p = 0.002) and 10% (p = 0.015) lower in the Maasai compared to the Luo and Kamba, respectively. Adjustments of SAT (range 0.1-7.1 cm) and VAT (range 1.5-14.2 cm) largely explained these inter-group differences with the Maasai having the highest combined abdominal fat accumulation. The Maasai had the highest insulin resistance and secretion, but the lowest relative beta-cell function compared to the Luo and Kamba. These differences were primarily explained by abdominal fat distribution.

Objective: To assess the prevalence of glucose intolerance in rural and urban Kenyan populations and in different ethnic groups. Further, to identify associations between lifestyle risk factors and glucose intolerance., Research Design and Methods: A cross-sectional study included an opportunity sample of Luo, Kamba, Maasai, and an ethnically mixed group from rural and urban Kenya. Diabetes and IGT were diagnosed using a standard OGTT. BMI, WC, AFA, AMA and abdominal subcutaneous and visceral fat thicknesses, physical activity and fitness were measured. Questionnaires were used to determine previous diabetes diagnosis, family history of diabetes, smoking habits, and alcohol consumption., Results: Among 1459 participants, mean age 38.6 years (range 17-68 years), the overall age-standardized prevalence of diabetes and IGT was 4.2% and 12.0%. The Luo had the highest prevalence of glucose intolerance among the rural ethnic groups. High BMI, WC, AFA, abdominal visceral and subcutaneous fat thickness, low fitness and physical activity, frequent alcohol consumption, and urban residence were associated with glucose intolerance., Conclusions: The prevalence of diabetes and IGT among different Kenyan population groups was moderate, and highest in the Luo. The role of lifestyle changes and ethnicity on the effect of diabetes in African populations needs further exploration.