The risk-benefit ratio for pioglitazone in the treatment of type 2 diabetes is unclear, according to a review of clinical trials, appearing in the October 18th online issue of The Cochrane Library.

Marketed by Takeda Pharmaceuticals and Eli Lilly & Co. as Actos, pioglitazone belongs to a class of drugs called thiazolidinediones that work by increasing the body’s sensitivity to insulin, to better control patients’ blood sugar. It is used alone or in combination with other drugs if diabetes can’t be controlled by diet and exercise.

After evaluating published scientific studies in which patients with type 2 diabetes were treated with pioglitazone, there was no “convincing evidence” that the drug reduced mortality, morbidity or adverse effects, or positively influenced health-related quality of life, lead author Dr. Bernd Richter, from Heinrich-Heine University in Dusseldorf, Germany, said in a statement.

Results from the United Kingdom Prospective Diabetes Study (UKPDS) and the University Group Diabetes Program (UGDP), the two biggest type 2 diabetes trials, also failed to show that the adverse effects of cardiovascular disease were lessened by improved metabolic control in diabetics.

Because it was unclear if newer drugs, such as pioglitazone, have a beneficial effect, Richter’s team performed a search of MEDLINE, EMBASE, and The Cochrane Library to identify clinical trials of 24 weeks’ duration or longer that evaluated pioglitazone as a treatment for type 2 diabetes.

Twenty-two trials were identified, which included roughly 6,200 people with type 2 diabetes. The longest duration of pioglitazone use was 34.5 months.

As noted, there was little evidence that treatment with pioglitazone improved patient outcomes. Moreover, the agent did not seem to provide superior metabolic control compared with other oral antidiabetic agents.

On the contrary, pioglitazone was more commonly associated with fluid retention than were other drugs, the report indicates.

“Pioglitazone treatment should be restricted to patients demonstrating real benefit of this therapy,” Richter concluded. Patient benefits should not be postulated on the basis of improvement of metabolic parameters…alone but should refer to patient-oriented outcomes such as fewer diabetic complications or better health-related quality of life.”

SOURCE: The Cochrane Library online, October 18, 2006.