Adipocytokines attenuate the association between visceral adiposity and diabetes in older adults
OBJECTIVE - To examine whether adiponectin is independently associated with diabetes and whether adiponectin and other adipocytokines account for the relationship between fat and diabetes. RESEARCH DESIGN AND METHODS - A nested case-control study from the Health, Aging, and Body Composition (Health ABC) Study. We measured four adipocytokines: adiponectin, interleukin (IL)-6, tumor necrosis factor-a, and plasminogen activator inhibitor 1 (PAl-1). Regional fat area was determined by computed tomography scan. The 519 case subjects had diabetes defined by fasting plasma glucose level greater than or equal to126 mg/dl or by use of diabetes medications. The 519 control subjects had normal glucose tolerance and were matched by sex, race, and study site. Sex-specific logistic models were adjusted for age, race, site, total adiposity, smoking, and physical activity. RESULTS- Higher adiponectin levels were associated with lower risk of diabetes (P < 0.001). Visceral fat was the only adiposity measure associated with diabetes after adjusting for BMI (odds ratio 3.0 [2.1-4.3] in women and 1.3 [1.0-1.6] in men, P < 0.001 between-sex comparison). Adipocytokines attenuated the association between visceral fat and diabetes for both sexes but more strongly in men (women 2.3 [1.5-3.3], men 1.1 [0.9-1.4]). In men, adiponectin, IL-6, and PAI-1 remained independently associated with diabetes after adjusting for fat depots; in women, adiponectin was the only independently associated adipocytokine. Controlling for insulin, HDL, triglycerides, and blood pressure did not change these results. CONCLUSIONS - Adiponectin is associated with lower odds of diabetes in older men and women. Whereas several adipocytokines explained the relationship between visceral adiposity and diabetes in men, only adiponectin partially mediated this association among women.