Comparison of pioglitazone and gliclazide in sustaining glycemic control over 2 years in patients with type 2 diabetes.

OBJECTIVE The hypothesis that pioglitazone treatment is superior to gliclazide treatment in sustaining glycemic control for up to 2 years in patients with type 2 diabetes was tested. RESEARCH DESIGN AND METHODS This was a randomized, multicenter, double-blind, double-dummy, parallel-group, 2-year study. Approximately 600 patients from 98 centers participated. Eligible patients had completed a previous 12-month study and consented to continue treatment for a further year. To avoid selection bias, all patients from all centers were included in the primary analysis (a comparison of the time-to-failure distributions of the two groups by using a log-rank test) regardless of whether they continued treatment for a 2nd year. By using repeated-measures ANOVA, time course of least square means of HbA(1c) and homeostasis model of assessment (HOMA) indexes (HOMA-%S and HOMA-%B) were analyzed. RESULTS A greater proportion of patients treated with pioglitazone maintained HbA(1c) <8% over the 2-year period than those treated with gliclazide. A difference between the Kaplan-Meier curves was apparent as early as week 32 and widened at each time point thereafter, becoming statistically significant from week 52 onward. At week 104, 129 (47.8%) of 270 pioglitazone-treated patients and 110 (37.0%) of 297 gliclazide-treated patients maintained HbA(1c) <8%. Compared with gliclazide treatment, pioglitazone treatment produced a larger decrease in HbA(1c), a larger increase in HOMA-%S, and a smaller increase in HOMA-%B during the 2nd year of treatment. CONCLUSIONS Pioglitazone is superior to gliclazide in sustaining glycemic control in patients with type 2 diabetes during the 2nd year of treatment.