A 20–23-week, double-blind study was conducted to determine the efficacy and tolerability of the combination of pioglitazone and a sulfonylurea in the treatment of poorly controlled type 2 diabetes (HbA_1c >8.0%) in patients who had been on a stable dose of a sulfonylurea for at least one month. Patients were randomized to treatment with their usual sulfonylurea treatment plus once-daily pioglitazone 15 mg (n=184), pioglitazone 30 mg (n=189), or placebo (n=187).

Patients who received pioglitazone plus a sulfonylurea had significant decreases from baseline (P<0.05) in HbA_1c and fasting plasma glucose levels compared with those who received placebo plus a sulfonylurea. Compared with placebo, patients treated with pioglitazone 15 mg had a mean decrease of HbA_1c of 0.9% (95% CI: 0.06% to 1.2%) and those treated with pioglitazone 30 mg had a mean decrease of HbA_1c of 1.3% (95% CI: 1% to 1.6%). Both pioglitazone groups had significant (P<0.05) decreases in triglyceride levels and increases in HDL-C levels compared with the placebo group. Pioglitazone was well tolerated. The adverse events rates were similar in all groups.

It was concluded that pioglitazone plus a sulfonylurea significantly improves HbA_1c and fasting plasma glucose levels and has beneficial effects on HDL-C and triglyceride levels.

Kipnes MS, Krosnick A, Rendell MS, et al. Pioglitazone hydrochloride in combination with sulfonylurea therapy improves glycemic control in patients with type 2 diabetes mellitus: a randomized, placebo-controlled study. Am J Med. 2001;111:10-17.
The above summary is adapted from the cited reference.