Objective: To compare short-term glycosylated hemoglobin (HbA(1c)), lipid, weight, tolerability, and hepatic effects after switching patients with type 2 diabetes from troglitazone to either pioglitazone or rosiglitazone treatment.
Methods: This study compared the effects of conversion from maintenance troglitazone therapy to pioglitazone versus rosiglitazone. HbA(1c), lipids, weights, adverse effects, and hepatic status were monitored, providing no other major therapeutic change had been made. Of 163 study candidates, 144 and 125 patients fulfilled the criteria for comparison of HbA(1c) and lipids, respectively.
Results: HbA(1c) decreased an absolute mean of 0.08% for each treatment group, after a mean 3.2-month observation. Mean cholesterol, triglyceride, and low-density lipoprotein (LDL) cholesterol levels decreased in the pioglitazone group by 4.7%, 11.3%, and 7.3% but increased 8.4%, 38.4%, and 8.1%, respectively, in the rosiglitazone group. Mean high-density lipoprotein (HDL) increased 2.6% with pioglitazone and decreased 6.3% with rosiglitazone therapy. Patients receiving a statin concomitantly when switched to rosiglitazone treatment had a 51.9% mean triglyceride increase versus a 25.7% increase for those not taking a statin, whereas the patients switched to pioglitazone therapy had respective decreases of 14.2% and 6.2%. Both drugs were generally well tolerated; patients in both groups had similar slight weight increases and no hepatic dysfunction.
Conclusion: Patients switched from maintenance troglitazone treatment to either pioglitazone or rosiglitazone therapy had similar glycemic control. Conversion to pioglitazone therapy caused a trend toward improvement in all lipid variables, but switching to rosiglitazone therapy caused significantly increased levels of cholesterol, triglycerides, and LDL and a trend toward decreased HDL. Patients already receiving statins when switched to rosiglitazone therapy had particularly notable triglyceride worsening. Whether these effects will lead to changes in cardiovascular outcome or will be maintained over a longer period remains to be established.