SOUTH-AFRICAN INDIANS SHOW A HIGH PREVALENCE OF NIDDM AND BIMODALITY IN PLASMA-GLUCOSE DISTRIBUTION PATTERNS

OBJECTIVE - To determine the prevalence of diabetes mellitus and impai red glucose tolerance (IGT) and to test for bimodality in the plasma g lucose distribution in South African Indians. RESEARCH DESIGN AND METH ODS - Subjects were selected by systematic cluster sampling in various areas of Durban. They underwent a modified glucose tolerance test whe reby fasting and 2-h postglucose (75 g) plasma glucose levels were mea sured. The program MIX was used to test for bimodality in the plasma g lucose distribution. RESULTS - We tested 2,479 subjects (1,441 women a nd 1,038 men). Based on the revised World Health Organization criteria , the crude prevalence of diabetes mellitus was 9.8%, and the crude pr evalence of IGT was 5.8%; the age- and sex-adjusted prevalence was 13. 0 and 6.9%, respectively. IGT was significantly more common in men (7. 6%) than in women (4.4%). Obesity was a feature of both diabetes melli tus and IGT, particularly in women. Both fasting and 2-h plasma glucos e values did not conform to a single normal distribution pattern in an y age-group, whereas unequivocal evidence of bimodality was seen in th e 55- to 74-year age-group of both sexes for fasting and 2-h glucose a nd also in the 2-h levels of men in the 25- to 34-year age-group. CONC LUSIONS - This study has highlighted a high prevalence of non-insulin- dependent diabetes mellitus in South African Indians and bimodality in the plasma glucose distribution.