Adiponectin in a native Canadian population experiencing rapid epidemiological transition

OBJECTIVE - Adiponectin is emerging as an important protein in the etiology of obesity and related metabolic disorders. The objectives of this study were to determine cross-sectional and prospective associations of adiponectin concentration with adiposity, type 2 diabetes, and cardiovascular disease (CVD) risk factors in a population-based Study of Native Canadians, a group experiencing dramatic increases in diabetes and CVD. RESEARCH DESIGN AND METHODS - During the 1993-1995 baseline survey, samples for glucose, insulin, adiponectin, and lipids were collected after an overnight fast. Waist circumference and percent body fat were measured, and a 75-g oral glucose tolerance test was administered: n = 505 With normal glucose tolerance (NGT), 74 with impaired glucose tolerance (IGT), and 149 with diabetes. In 1998, 95 high-risk subjects, defined as those who, at baseline, had either IGT or NGT with an elevated 2-h glucose concentration (greater than or equal to7.0 mmol/l), participated, in a follow-up examination using the protocol used at baseline. RESULTS - After adjustment for covariates including percent body fat and homeostasis model assessment of insulin resistance (HOMA-IR), adiponectin concentrations were significantly lower among men versus women (10.8 vs. 15.0 mug/ml, P < 0.0001.) and among diabetic versus NGT subjects (11.1 vs. 13.1 mug/ml, P < 0.05). Adiponectin was inversely correlated with percent body fat, waist circumference, HOMA-IR, and triglyceride and Positively correlated with HDL (r = \0.30\ -\0.44\, all P < 0.0001). In multivariate linear regression analysis in nondiabetic adiponectin variaton among subjects, HDL and percent body fat were significantly related to a both men and women (R-2 = 28-29%). Factor analysis returned three underlying factors among these variables, with adiponectin loading on the second factor along with insulin, waist circumference, triglyceride, and HDL. In the follow-up Study, higher adiponectin at baseline was significantly associated with increases in HDL (r = 0.24, P = 0.03) and decreases in HOMA-IR (r = -0.29, P = 0.009) after adjustment for covanates, including age, adiposity, and diabetes status at baseline and follow-up. CONCLUSIONS - These population-based findings support the hypothesis that low circulating levels of adiponectin are an important determinant of risk of CVD.