Thiazolidinediones: comparison of long-term effects on glycemic control and cardiovascular risk factors

OBJECTIVE: To compare the long-term effects on HbA(1c), lipid parameters, body weight, and hepatotoxicity after switching type 2 diabetes patients from troglitazone to either pioglitazone or rosiglitazone. METHODS: Of 125 study candidates from a previous prospective study, 100 patients (51 pioglitazone, 49 rosiglitazone) met criteria for comparing HbA(1c), lipids, body weight, and incidence of hepatotoxicity over 2 successive observation periods (3.1 and 12.6 months). RESULTS: Mean absolute HbA(1c) decreased significantly, 0.53 and 0.27% in the pioglitazone and rosiglitazone groups, respectively, at the 12.6-month observation. Mean triglyceride (TG) decreased in the pioglitazone group at each interval with a cumulative decrease of 26.4% from baseline. In contrast, TG increased in the rosiglitazone patients by 43.3% at 3.1 months and then decreased (but remained above baseline) at 12.6 months. Mean high density lipoprotein (HDL) increased 22.1% with pioglitazone and 13.3% with rosiglitazone. In patients who had a baseline HDL < 35 mg/dL (0.91 mmol/L), pioglitazone treated patients experienced a significant increase at each interval resulting in a 52.6% increase in HDL compared to a 26.9% increase for rosiglitazone patients. Patients in both treatment groups had similar weight increases at each interval and no hepatotoxicity was noted. CONCLUSION: With pioglitazone or rosiglitazone, changes in glycemic control, lipid effects, and body weight appear to continue over time. Pioglitazone treatment resulted in decreased triglyceride levels, while rosiglitazone was associated with an increase in triglyceride levels. HDL increased in both treatment groups, but in patients with a baseline HDL < 35 mg/dL (0.91 mmol/L), pioglitazone improved the HDL to a greater extent than rosiglitazone.