Effects of Pioglitazone in Combination with Metformin or a Sulfonylurea Compared to a Fixed-Dose Combination of Metformin and Glibenclamide in Patients with Type 2 Diabetes

Abstract

Background:

This study was designed to compare the effectiveness of co-administration of pioglitazone with metformin or a sulfonylurea (SU), with a fixed-dose combination of metformin and glibenclamide on glycemic control and β-cell function in patients with type 2 diabetes.

Methods:

Patients (n = 250) treated with metformin (≤3 g/day) or an SU as monotherapy for >3 months and with glycosylated hemoglobin (HbA_1c) between 7.5% and 11% inclusive were randomized to receive either pioglitazone (15–30 mg/day) as add-on therapy to metformin or an SU or a fixed-dose combination of metformin (400 mg) and glibenclamide (2.5 mg) (up to three tablets per day) for 6 months. HbA_1c and fasting plasma glucose (FPG) were measured at baseline and 2, 4, and 6 months. C-peptide levels were measured at baseline and 6 months, and post-challenge glucose and insulin responses were measured.

Results:

After 6 months, pioglitazone-based and fixed-dose metformin + glibenclamide resulted in similar reductions in HbA_1c (−1.11% vs. −1.29%, respectively; P = 0.192) and FPG (−2.13 vs. −1.81 mmol/L, respectively; P = 0.370). Patients treated with pioglitazone for 6 months had significantly reduced C-peptide levels compared with baseline (−0.09 nmol/L, P = 0.001), while patients receiving fixed-dose metformin + glibenclamide combination had slightly increased C-peptide levels (+0.04 nmol/L, P = 0.08). Pioglitazone treatment also improved post-challenge insulin responses.

Conclusions:

Co-administration of pioglitazone with metformin or an SU is an effective alternative to fixed-dose metformin + glibenclamide combination for patients with type 2 diabetes. The complementary effects of pioglitazone with either metformin or an SU may also have the potential to preserve β-cell function and delay the progression of type 2 diabetes.