Objective: To investigate the effects of rosiglitazone on serum leptin and insulin resistance (IR) in patients with Type 2 diabetes and to determine the correlation between IR and serum leptin.
Methods: Thirty-nine Type 2 diabetic patients were given rosiglitazone (4 mg/d) for 12 weeks. The changes of height,weight, fasting plasm glucose (FPG), fasting serum insulin (FINS), serum leptin, hepatic and renal function and serum lipid were examined at the baseline and 12 weeks after the therapy. We used the HOMA model to calculate HOMA-IR as an index of insulin resistance. We also calculated the insulin sensitivity index (ISI). The correlation among the above detected markers was analyzed using multiple regression analysis and partial correlation analysis, respectively.
Results: The serum leptin level, FINS, and HOMA-IR were higher (P < 0.01), but ISI was lower in the diabetic patients than those of the normal controls before the treatment. BMI, hepatic function, renal function, and serum lipid level did not significantly change, while FPG, FINS, and HOMA-IR were reduced significantly after the 12-week treatment (P < 0.01). ISI was obviously higher than that before the treatment (P < 0.01). Bivariate analysis showed that the serum leptin was positively correlated with FINS and HOMA-IR (r1 = 0.525, P < 0.01, r2 = 0.391, P < 0.05), but negatively correlated with ISI (r = -0.334, P < 0.05). Multiregressive analysis revealed that the most important factors affecting the leptin in Type 2 diabetes were sex, BMI, TG, FINS, and ISI (R2 = 0.358, P < 0.01).
Conclusion: There is close correlation between IR and higher serum leptin level in patients with Type 2 diabetes. Rosiglitazone can reduce FPG level and serum leptin and improve the insulin resistance in patients with Type 2 diabetes.