In 2021 alone, clinicians wrote more than 91 million orders for the medication — up from 40 million 2004.
But is metformin just getting started? Emerging evidence suggests the drug may be effective for a much broader range of conditions beyond managing high blood glucose, including various cancers, obesity, liver disease, cardiovascular, neurodegenerative, and renal diseases. As the evidence for diverse uses accumulates, many trials have launched, with researchers looking to expand metformin’s indications and validate or explore new directions.
Metformin’s long history as a pharmaceutical includes an herbal ancestry, recognition in 1918 for its ability to lower blood glucose, being cast aside because of toxicity fears in the 1930s, rediscovery and synthesis in Europe in the 1940s, the first reported use for diabetes in 1957, and approval in the United States in 1994.
The drug has maintained its place as the preferred first-line treatment for type 2 diabetes since 2011, when it was first included in the World Health Organization’s essential medicines list.
“The focus hitherto has been primarily on its insulin sensitization effects,” Akshay Jain, MD, a clinical and research endocrinologist at TLC Diabetes and Endocrinology, in Surrey, British Columbia, Canada, told this news organization.
“The recent surge of renewed interest is in part related to its postulated effects on multiple other receptors,” he said. “In my mind, the metformin data on coronary artery disease reduction and cancer-protective effects have come farther along than other disease states.”
Cardiovascular Outcomes
Gregory G. Schwartz, MD, PhD, chief of the cardiology section at Rocky Mountain Regional VA Medical Center and professor of medicine at the University of Colorado School of Medicine in Aurora, is leading the VA-IMPACT trial. Despite metformin’s long history and widespread use, he said his study is the first placebo-controlled cardiovascular outcomes trial of the drug.
Launched in 2023, the study tests the hypothesis that metformin reduces the risk for death or nonfatal ischemic cardiovascular events in patients with prediabetes and established coronary, cerebrovascular, or peripheral artery disease, Dr. Schwartz said. The trial is being conducted at roughly 40 VA medical centers, with a planned enrollment of 7410 patients. The estimated completion date is March 2029.
“The principal mechanism of action of metformin is through activation of AMP [adenosine monophosphate]–activated protein kinase, a central pathway in metabolic regulation, cell protection, and survival,” Dr. Schwartz explained. “Experimental data have demonstrated attenuated development of atherosclerosis, reduced myocardial infarct size, improved endothelial function, and antiarrhythmic actions — none of those dependent on the presence of diabetes.”
Dr. Schwartz and his colleagues decided to test their hypothesis in people with prediabetes, rather than diabetes, to create a “true placebo-controlled comparison,” he said.
“If patients with type 2 diabetes had been chosen, there would be potential for confounding because a placebo group would require more treatment with other active antihyperglycemic medications to achieve the same degree of glycemic control as a metformin group,” Dr. Schwartz said.
“If proven efficacious in the VA-IMPACT trial, metformin could provide an inexpensive, generally safe, and well-tolerated approach to reduce cardiovascular morbidity and mortality in a large segment of the population,” Dr. Schwartz added. “Perhaps the old dog can learn some new tricks.”
Other recruiting trials looking at cardiovascular-related outcomes include Met-PEF, LIMIT, and Metformin as an Adjunctive Therapy to Catheter Ablation in Atrial Fibrillation.