Standard definitions of overweight and central adiposity for determining diabetes risk in Japanese Americans

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Abstract
Background: Despite having lower average body mass indexes (BMIs) than do whites, Asians are at high risk of type 2 diabetes, possibly because of their greater central adiposity. The criteria for identifying individuals at risk of obesity-related conditions are usually not population specific. Objective: Our goal was to determine whether the National Heart, Lung, and Blood Institute (NHLBI) overweight and obesity guidelines are useful for identifying diabetes risk in Japanese Americans. Design: This was a prospective, cohort study of 466 nondiabetic Japanese Americans [age: 52.2 ± 0.6 y; BMI (in kg/m2): 24.1 ± 0.2; x̄ ± SEM]. Diabetes status at a 5-y follow-up visit was assessed with an oral-glucose-tolerance test. Results: Among 240 subjects aged ≤55 y, incident diabetes was strongly associated with overweight (BMI ≥ 25) at baseline [relative risk (RR): 22.4; 95% CI: 2.7, 183; adjusted for age, sex, smoking, and family history] and weight gain of >10 kg since the age of 20 y (adjusted RR: 4.5; 95% CI: 1.4, 14.5). NHLBI definitions of central obesity (waist circumference ≥ 88 cm for women and ≥ 102 cm for men) were unsuitable for this population because only 15 of 240 subjects met these criteria. A waist circumference greater than or equal to the third tertile was associated with diabetes (adjusted RR: 5.4; 95% CI: 1.7, 17.0). Among 226 subjects aged >55 y, incident diabetes was not associated with BMI, weight gain, or waist circumference. Conclusions: NHLBI definitions are useful for identifying overweight Japanese Americans aged <55 y who are at high risk of diabetes. Although central adiposity is an important risk factor, the guidelines for waist circumference are insensitive predictors of diabetes risk in this population.