Metformin fails to improve outcomes for heart failure patients
Metformin, a popular type 2 diabetes medication used to reduce blood glucose levels, does not appear to make a significant impact on outcomes for patients with heart failure with reduced ejection fraction (HFrEF). That is according to two separate studies presented at European Society of Cardiology (ESC) Congress 2026.
The first of the two studies, Met-HeFT, included 940 heart failure patients in Denmark who either presented with type 2 diabetes or face an increased risk of developing type 2 diabetes. The mean age was 70 years old, and 84% of patients were men. Study participants were randomized to either undergo treatment with metformin or a placebo.
Overall, after a mean follow-up period of 3.7 years, there was no significant difference in the study’s primary endpoint—a composite of mortality, worsening heart failure symptoms, acute myocardial infarction or stroke—between the two groups. That outcome occurred in 25.1% of metformin patients and 23.4% of placebo patients. Secondary endpoints, including new-onset diabetes and unplanned heart failure rates, were also not significant different between the two treatment options.
It is worth noting, however, that just approximately one in 10 patients presented with type 2 diabetes. The remaining patients were all determined to face a heightened risk of developing type 2 diabetes.
“Our lack of enrollment of patients with type 2 diabetes likely reflected the existing widespread use of metformin and the reluctance of patients and clinicians to discontinue ongoing metformin treatment, which was a requirement for inclusion,” Professor Henrik Wiggers with Aarhus University Hospital in Denmark, principal investigator of Met-HeFT, said in a statement.
The other ESC analysis focused on this topic was a meta-analysis that included data from Met-HeFT and a selection of other clinical trials. Overall, researchers examined data from more than 2,000 patients who were either treated with metformin or a placebo. Its findings were the same as Met-HeFT: metformin did not protect the hearts of these patients.
“Metformin was not associated with any harm and it still remains beneficial in terms of glucose lowering, but our analyses indicate no significant evidence for any independent cardioprotective benefits,” Wiggers noted.
Michael has more than 19 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.