Rosiglitazone therapy improves insulin resistance parameters in overweight and obese diabetic patients intolerant to metformin.

Background: Few studies have directly compared rosiglitazone and metformin effects on adipocytokines. The aim was to observe the possible effects of rosiglitazone and metformin on glycemic control, insulin sensitivity, plasma leptin (pL), adiponectin (ADN), tumor necrosis factor-alpha (TNF-alpha), and resistin (R) in overweight and obese diabetic patients intolerant to metformin.
Methods: Six hundred and ninety-four consecutive overweight and obese type 2 diabetic patients were evaluated and 56 patients were intolerant to metformin at maximum dosage. We added rosiglitazone to metformin in these intolerant patients (RM) and we compared them with 61 patients treated with metformin (M) in a single-blind placebo-controlled trial. We evaluated body mass index (BMI), glycated hemoglobin (HbA(1c)), fasting plasma glucose (FPG), fasting plasma insulin (FPI), pL, ADN, TNF-alpha, and R at baseline and after 3 and 6 months. Furthermore, we calculated insulin resistance index (HOMA-index) using FPG and FPI.
Results: Glycated hemoglobin, FPG, FPI, and HOMA-index results were lower than baseline values in RM and M groups. Glycated hemoglobin and HOMA-index values were significantly lower in RM group compared to M group at 6 months. Plasma leptin, ADN, TNF-alpha, and R were significantly improved in RM group compared to M group at 6 months.
Conclusions: No BMI change was observed, probably because rosiglitazone was added to metformin, that could mitigate the body increase of rosiglitazone. Rosiglitazone improved glycemic control and insulin resistance-correlated parameters when added to intolerant metformin patients. These data suggest that rosiglitazone may be the drug of choice for the treatment of overweight and obese type 2 diabetic patients.