Long-term effects of troglitazone: open-label extension studies in type 2 diabetic patients

Abstract

Objective: To determine the long-term effects of troglitazone as monotherapy or in combination with sulfonylureas or insulin regarding glycemic and lipid measures.

Research design and methods: Patients who completed one of three double-blind studies (a 6-month troglitazone monotherapy study, a 52-week study of troglitazone in combination with micronized glyburide, or a 6-month study of troglitazone in combination with insulin) were allowed to enter open-label extensions of their respective double-blind studies. Troglitazone dose titrations were allowed to a maximum of 600 mg in response to inadequate glycemic control during the open-label phases of troglitazone monotherapy or sulfonylurea combination therapy but not with insulin combination therapy. This article focuses on the effectiveness of the highest dose of troglitazone used in these studies (600 mg daily). Safety data from all patients studied at all doses are also presented.

Results: For patients who received a fixed dose of 600 mg troglitazone, mean changes in fasting serum glucose and HbA1c levels from baseline to the end of the open-label phase were -57 mg/dl and -0.4%, respectively (monotherapy); -49 mg/dl and -1.8%, respectively (sulfonylurea combination); and -31 mg/dl and -1.0%, respectively (insulin combination). The proportion of patients achieving an HbA1c level of < or =8% from the combined cohort of all three studies was 54% versus only 19% at baseline. The mean decrease in triglycerides from baseline to the end of the open-label phase was 18% among all patients in the three studies who received a fixed dose of 600 mg troglitazone. Troglitazone was well tolerated in these three open-label studies; a total of 758 patients completed a total exposure of 16,264 patient-months to troglitazone in these three studies with minimal adverse events.

Conclusions: Long-term use of troglitazone alone or in combination with sulfonylureas or insulin is safe and effective in sustaining glycemic control and in reducing hypertriglyceridemia in type 2 diabetic patients.