Plasma resistin, adiponectin and leptin levels in lean and obese subjects: correlations with insulin resistance

Objective: Adipose tissue regulates insulin sensitivity via the circulating adipocytokines, leptin, resistin and adiponectin. The objective of this study was to compare the levels of resistin, adiponectin and leptin in lean and obese subjects and determine the relationship between circulating adipocytokines and insulin resistance. Methods: We examined plasma levels of resistin, adiponectin and leptin in 17 lean subjects with a mean body mass index (BMI) of similar to23 and 34 non-diabetic obese individuals with a mean BMI similar to33. Insulin resistance was assessed using the homeostasis model assessment ratio (HOMA-R) formula derived from fasting insulin and glucose levels. Results: Resistin levels were not significantly different between the two groups but were significantly higher in women compared with men, 35.4 +/- 6.5 (S.E.) vs 15.4 +/- 2.9 mug/l, P < 0.01. Resistin did not correlate with BMI but did significantly correlate with HOMA-R, P < 0.01, and this correlation remained significant after adjustment for gender and BMI. Adiponectin levels were significantly lower in obese compared with lean subjects, P < 0.005, and higher in women, P < 0.001, but showed no significant correlation with HOMA-R. Leptin levels were significantly higher in obese subjects and women and correlated with HOMA-R and resistin. Discussion: In this small group of patients we demonstrated that insulin resistance correlated most strongly with leptin levels. A significant correlation between resistin levels and insulin resistance was also observed. Although a similar trend was apparent for adiponectin, the correlation with insulin resistance did not achieve statistical significance.