Two new studies have once again called into question the safety of GlaxoSmithKline’s type 2 diabetes drug Avandia.

Both studies were published Sept. 11 in the Journal of the American Medical Association (JAMA).

One of the new studies, a meta-analysis co-authored by Dr. Steven Nissen of the Cleveland Clinic, found that Avandia rival drug, Takeda’s Actos, appeared to protect patients from heart attacks, stroke and death by 18%. It was also Nissen who first published results of a meta-analysis in the New England Journal of Medicine in May that linked the Avandia to an increased risk of heart attack.

GSK has defended Avandia’s safety with data from its own clinical trials and criticized Nissen’s May meta-analysis methodology, which combined the results from different studies. 

The second of the two new studies published in JAMA backs up Nissen’s earlier findings on Avandia. The second study, also a meta-analysis, was conducted by a team from Wake Forest University. The Wake Forest team found the Avandia increased the risk of heart attack by 42%. Nissen’s earlier survey found a 43% increased risk.

GSK said in a statement posted on their Web site that the conclusions of the JAMA studies “do not confirm a difference in the safety profile of Avandia (rosiglitazone) and Actos (pioglitazone).” The statement added that the studies “do not yield data robust enough to guide doctors in selecting appropriate diabetes treatments for their patients.”