Association Between Serum Leptin and Adiponectin Levels with Risk of Insulin Resistance and Impaired Glucose Tolerance in Non-diabetic Women

Obesity is a well known risk factor for insulin resistance and type 2 diabetes. Recently discovered adipocyte-derived proteins (leptin and adiponectin) might contribute to the pathologic mechanism linking obesity and insulin resistance. A total of 190 non-diabetic women were recruited from the Obesity Clinic of Kaohsiung Municipal Hsiao-Kang Hospital, Taiwan, between February 2003 and February 2004. All participants completed a simple questionnaire. Blood pressure and body mass index were measured; blood samples for fasting glucose, total cholesterol, high-density lipoprotein cholesterol, triglyceride, leptin, adiponectin, and fasting insulin level were collected after an overnight fast. Two-hour glucose level after a 75-g glucose tolerance test was determined. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated as the index of insulin resistance. Multivariate linear regression analyses were used to analyze the relationship between adipocytokines and insulin resistance after adjusting for possible confounding factors. Leptin and adiponectin were found to be independently associated with HOMA-IR and fasting insulin concentration, but in divergent directions, after adjusting for potential confounding factors. Adiponectin, but not leptin, was associated with impaired glucose tolerance after adjusting for potential confounding factors. The results suggest that leptin and adiponectin may be involved in the pathophysiologic link between obesity and insulin resistance independently. Low levels of adiponectin may increase the risks of developing impaired glucose metabolism and type 2 diabetes.