A long-term comparison of pioglitazone and gliclazide in patients with Type 2 diabetes mellitus: a randomized, double-blind, parallel-group comparison trial

Aims This study compared the effects of pioglitazone and gliclazide on metabolic control in drug-naive patients with Type 2 diabetes mellitus. Methods A total of 1270 patients with Type 2 diabetes were randomized in a parallel-group, double-dummy, double-blind study. Patients with poorly controlled Type 2 diabetes (HbA(1c) 7.5-11%), despite dietary advice, received either pioglitazone up to 45 mg once daily or gliclazide up to 160 mg two times daily. Primary efficacy endpoint was change in HbA(1c) from baseline to the end of the study. Secondary efficacy endpoints included change in fasting plasma glucose, fasting plasma insulin and plasma lipids. At selected centres, oral glucose tolerance tests were performed and C-peptide and pro-insulin levels were measured. Results Mean HbA(1c) values decreased by the same amount in the two treatment groups from baseline to week 52 [pioglitazone: -1.4%; gliclazide: -1.4%; (90% CI: -0.18 to 0.02)]. A significantly greater mean reduction in fasting plasma glucose was observed in the pioglitazone group (2.4 mmol/l) than in the gliclazide group [2.0 mmol/l; treatment difference -0.4 mmol/l in favour of pioglitazone; P = 0.002; (95% CI: -0.7 to -0.1)]. Improvements in high-density lipoprotein cholesterol (HDL-C) and total cholesterol/HDL-C were greater with pioglitazone than with gliclazide (P < 0.001). The frequencies of adverse events were comparable between the two treatment groups, but more hypoglycaemic events were reported for gliclazide, whereas twice as many patients reported oedema with pioglitazone than with gliclazide. Conclusions Pioglitazone monotherapy was equivalent to gliclazide in reducing HbA(1c), with specific differences between treatments in terms of mechanism of action, plasma lipids and adverse events.