Do measures of body fat distribution provide information on the risk of type 2 diabetes in addition to measures of general obesity? Comparison of anthropometric predictors of type 2 diabetes in Pima Indians.

OBJECTIVE: To investigate which anthropometric measurements of obesity best predict type 2 diabetes in a population of Pima Indians and whether additional information on diabetes risk could be obtained by combining measures of general obesity with measures of body fat distribution.

RESEARCH DESIGN AND METHODS: We conducted a prospective study of 624 men and 990 nonpregnant women >18 years of age without diabetes. Subjects were followed a mean of 5.25 years for the development of type 2 diabetes (using 1997 American Diabetes Association criteria).

RESULTS: A total of 322 new cases of type 2 diabetes (107 men and 215 women) were diagnosed during follow-up. Baseline obesity measurements were highly correlated and predicted diabetes in proportional hazards models adjusted for age. BMI had the highest hazard ratio in men and women, with age-adjusted hazard ratios per SD of 1.73 (95% CI 1.44-2.07) and 1.67 (1.45-1.91), respectively. According to receiver-operating characteristic analysis, BMI and waist-to-height ratio were the best predictors of diabetes in men, while in women BMI, waist-to-height ratio, waist circumference, and waist-to-thigh ratio were the best predictors. The predictive abilities of models containing BMI were not significantly improved by including other measures of general obesity or measures of the body fat distribution.

CONCLUSIONS: Throughout its range, BMI was an excellent predictor of type 2 diabetes risk in Pima Indians and was not significantly improved by combining it with other measures of general adiposity or body fat distribution.