Obesity and insulin resistance are the hallmarks of abnormal glucose tolerance (Abnl-GT) in African Americans and African Caribbeans. In contrast, prevalence, phenotype and etiology of Abnl-GT in African-born blacks are unknown. Working with African-born blacks living in America, we determined (a) the prevalence of Abnl-GT, and (b) the etiology of Abnl-GT by BMI category (i.e., primary β-cell failure vs. insulin resistance). OGTT was performed in 461 African-born blacks (male: 66%; age: 39±10 (mean±SD), range: 20-65y; BMI: 27.6±4.5, range: 18.4-42.4 kg/m2). Abnl-GT was diagnosed by glycemia: 0h glucose≥100 or 2h glucose≥140 mg/dL. Insulin resistance was defined by the cutoff at the lowest quartile of the Matsuda Index for the population (≤2.97). Primary β-cell failure was diagnosed if Abnl-GT was present and Matsuda Index was >2.97. Obesity occurred in 27% (123/461). Abnl-GT occurred in 38% (173/461). By BMI category, Abnl-GT occurred in 35% (117/338) of the nonobese and 46% (56/123) of the obese. Overall, β-cell failure occurred in 61% (105/173) of participants with Abnl-GT (Figure). Yet, the odds of primary β-cell failure as the cause of Abnl-GT were 4 times higher in the nonobese than the obese (OR: 4.2; 95% CI: 2.2, 8.3). In short, the prevalence of Abnl-GT was high in both nonobese and obese African-born blacks. However, in nonobese Africans with Abnl-GT, primary β-cell failure was more common than insulin resistance.
A.F. Hobabagabo: None. T. Hormenu: None. E.M. Shoup: None. N.H. Osei-Tutu: None. C. DuBose: None. L. Mabundo: None. S.T. Chung: None. A.E. Sumner: None.