Pioglitazone Improves Lipid Profiles More Effectively than Rosiglitazone

Source: Gegick CG, Altheimer MD. Endocr Pract. 2001;7:162-169.

The objective of this study was to compare short-term glycosylated hemoglobin (HbA1c), lipid, weight, tolerability, and hepatic effects after switching patients with type 2 diabetes from troglitazone to either pioglitazone or rosiglitazone treatment.

A total of 144 and 125 patients met the criteria for comparison of HbA1c and lipids, respectively. HbA1c decreased 0.08% for each treatment group, after a mean 3.2 months of observation. Mean cholesterol, triglyceride, and low-density lipoprotein (LDL) cholesterol levels decreased in the pioglitazone group by 44.7%, 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 by 6.3% with rosiglitazone.

Table: Lipid Changes After Changing From Troglitazone
Lipid  Before After
mg/dL mg/dL
Total Cholesterol 190.6 181.6
Triglycerides 208.5 184.9
HDL 46.7 47.9
LDL 104.6 97.0
Total Cholesterol 180.0 195.0
Triglycerides 178.7 247.4
HDL 44.1 41.3
LDL 100.0 108.1

Patients receiving a statin concomitantly when switched to rosiglitazone treatment had a 51.9% increase in mean triglyceride levels vs. a 25.7% increase in those not receiving a statin, whereas the patients switched to pioglitazone therapy had respective decreases of 14.2% and 6.2%. Both drugs were generally well tolerated and had similar slight weight increases and no hepatic dysfunction.

Switching to pioglitazone caused a trend toward lipid profile improvement, but switching to rosiglitazone therapy caused a significant increase in all lipids, except HDL, which was lowered. Patients receiving statins when switched to rosiglitazone had particularly notable triglyceride worsening. Whether these effects will lead to changes in cardiovascular outcome or will be maintained over a longer period of time remains to be established.

Comment by Ralph R. Hall, MD, FACP

Despite the short-term nature of this study and the lack of patient randomization, these are remarkable changes in risk patterns. Further, this is how it happens in our practices. Other medications such as metformin, monotherapy with troglitazone, sulfonylurea treatment, and others were similar for each group of patients.

The changes seen in HDL cholesterol and triglycerides suggest that the patients switched to rosiglitazone had an increase in the more atherogenic small dense LDL. With these changes and the availability of pioglitazone, it would be difficult to maintain treatment with rosiglitazone until more safety and long-term studies were completed.

One other item of note is that these patients had been treated for their HbA1c and lipid goals prior to the change from troglitazone to the other thiazolidinediones. The study also demonstrates that the national goals for HbA1c and lipids can be met in clinical practice.

Dr. Hall is Emeritus Professor of Medicine, University of Missouri-Kansas City School of Medicine, Kansas City, Mo.