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Objective: This prospective study evaluates the effect of insulin sensitizers, pioglitazone (PGZ) and metformin (MET) on plasma adiponectin and leptin levels in subjects newly diagnosed with type 2 diabetes mellitus (T2DM).

Design: Double blind, randomized, active control, dose escalation study of 12 weeks treatment duration.

Patients: Thirty apparently healthy, treatment-naive T2DM patients diagnosed within the past 6 months.

Measurements: Plasma adiponectin and leptin levels were estimated by enzyme-linked immunosorbent assay (ELISA), and insulin resistance by the homeostasis model of assessment (HOMA-IR).

Results: Baseline plasma levels of adiponectin were lower in diabetic (n = 30) subjects than matched controls (n = 10, 6[middle dot]6 /- 1[middle dot]1 vs 10[middle dot]4 /- 4[middle dot]2 [mu]g/ml, P = 0[middle dot]021). The 12-week treatment with PGZ significantly increased adiponectin concentrations (6[middle dot]6 /- 1[middle dot]1-17[middle dot]9 /- 7[middle dot]4 [mu]g/ml, P < 0[middle dot]001) with no alteration in the MET treated group (6[middle dot]8 /- 1[middle dot]5-6[middle dot]7 /- 2[middle dot]8 [mu]g/ml, P = 0[middle dot]9). A significant decrease in plasma leptin levels was observed in the MET treated group (32[middle dot]0 /- 28[middle dot]9-21[middle dot]4 /- 23[middle dot]3 ng/ml, P = 0[middle dot]024) but not in the PGZ treated group (23[middle dot]9 /- 24[middle dot]1-22[middle dot]4 /- 25[middle dot]4 ng/ml, P = 0[middle dot]69). The alterations in plasma adiponectin and leptin levels were not associated with any change in body mass index (BMI). PGZ therapy improved insulin sensitivity to a greater degree (P = 0[middle dot]007 and P = 0[middle dot]001 for fasting plasma insulin (FPI) and HOMA-IR, respectively) than MET (P = 0[middle dot]75 and P = 0[middle dot]02 for FPI and HOMA-IR, respectively) but this improvement was not significantly different from that of MET at the end of 12 weeks (P = 0[middle dot]146 and P = 0[middle dot]09 for FPI and HOMA-IR, respectively). However, improvement in insulin sensitivity with PGZ was not commensurate with the increase in adiponectin. Better control of postbreakfast plasma glucose (PBPG) as well as decrease in serum triglycerides (TGs) were also seen with PGZ (PBPG, P < 0[middle dot]001; TGs, P = 0[middle dot]013). The rest of the parameters were comparable. Adverse reactions reported were minor and did not result in treatment discontinuation.

Conclusions: Pioglitazone therapy appears to be better in achieving glycaemic control and increasing plasma adiponectin and insulin sensitivity in newly detected type 2 diabetics.

Copyright (C) 2006 Blackwell Publishing Ltd.