In patients with type 2 diabetes mellitus, all therapeutic options should be evaluated for their effect on cardiovascular risk factors, in addition to glycemic control.
A meta-analysis of randomized controlled trial of pioglitazone and Rosiglitazone i...
In patients with type 2 diabetes mellitus, all therapeutic options should be evaluated for their effect on cardiovascular risk factors, in addition to glycemic control.
A meta-analysis of randomized controlled trial of pioglitazone and Rosiglitazone in patients with type 2 diabetes was conducted to evaluate the effects of each drug on glycemic control, lipids, blood pressure, and weight. In addition, this study was aimed to identify if there is ethnic difference in the effects between Asian and western patients by subgroup analysis.
Among the randomized controlled trials of pioglitazone or rosiglitazone which had been published until February 2008, sixty-three randomized controlled trials that were eligible for the inclusion/exclusion criteria were collected. For quantitative meta-analysis, the weighted pooled effect sizes and their 95% confidence intervals were calculated by fixed effect model and random effect model.
The results of this study are as follows.
First, the effects of pioglitazone on the cardiovascular risk factors were mostly positive. Pioglitazone significantly lowered fasting plasma glucose and triglyceride level and increased high-density lipoprotein cholesterol (HDL-C) level. Some negative effects were also observed when the administration dose was more than 30mg, which were increase of low-density lipoprotein cholesterol (LDL-C) and total cholesterol level, and weight gain. There was no improvement of the effects when administration dose was increased from 30mg to 45mg.
Second, rosiglitazone significantly lowered hemoglobin A1C level and fasting plasma glucose, on the other hand, it increased all kinds of lipids (HDL, LDL, TG, total cholesterol), and demonstrated neutral effect on blood pressure and weight. The overall effect sizes were higher when the administration dose was 8mg than when it was 4mg, which shows that the therapeutic effects increased with dose increasing.
Third, when the effects of the two thiazolidinediones were compared, glucose lowering effect was higher in rosiglitazone. Pioglitazone produced a more favorable lipid profile. Both thiazolidinediones demonstrated similar increases in body weight. And the effect on blood pressure was slightly higher in pioglitazone.
Fourth, the effects of pioglitazone on the cardiovascular risk factors in two different ethnic groups were compared. The pooled effect sizes of both group administered 15mg of pioglitazone were very similar in all parameters. And when the effects of pioglitazone in western patients group at dose of 30mg and Asian patients group at dose of 15mg were compared, the overall effects sizes of almost all parameters including blood glucose level were higher in western patients group than that of Asian patients group. Therefore, we could conclude that the effects of pioglitazone on the cardiovascular risk factors are almost same in different ethnic groups.
Fifth, in comparison of the effects on the cardiovascular risk factors of rosiglitazone in the two ethnic groups, the pooled effect sizes of Asian patients group administered 4mg were higher than western patients group administered the same dose. Furthermore, in comparison of the effect sizes of Asian patients group administered 4mg and western patients group administered 8mg, the effect sizes were rather similar than they administered the same dose. Consequently, we evaluated that effects of rosiglitazone on the cardiovascular risk factors varies with ethnic difference.
However, the results above are partially different, as it is generally known as before in Korea, Therefore, a large, high-quality, direct comparative clinical trial including all kinds of ethnic group is needed to confirm this results.
One of the meanings of this study is that it provides information for choosing the appropriate TZD for patients according to their lipid level by showing that the two TZD drugs have differences in their effects on the cardiovascular risk factors in type 2 diabetic patients. In addition, this study is meaningful as the first trial to identify the ethnic difference in TZD drugs’ effects by applying meta-analysis method.
Well-designed head-to-head comparative trials as well as long-term cardiovascular outcome studies should be conducted in order to accurately determine the various effects of the two thiazolidinediones including their effects on different ethnic groups.