Metformin lowers risk of HF hospitalization in those with T2D

Metformin use is linked to a lower risk of hospitalization for heart failure in patients with type 2 diabetes, a paper in the Journal of the American Heart Association confirms.

In Taiwan, where Chin-Hsiao Tseng, MD, PhD, conducted his research, the annual incidence of hospitalization for heart failure was 88 per 100,000 population in younger patients and 2,181 per 100,000 population in older patients in 2005. HF admits were in the hospital for 15.8 days on average that year, and in-hospital mortality reached 3.9%.

So it’s important to address the issue of heart failure in the country—especially with a rapidly aging global population—Tseng, of National Taiwan University Hospital in Taipei, wrote in JAHA. And metformin, a first-line treatment for type 2 diabetes, has been recognized as a possible mediator for those with HF.

“Because of a potential risk of fatal lactic acidosis, metformin has long been underprescribed, especially in patients with HF,” Tseng wrote. “This condition has much improved after recent epidemiological studies showing that the risk of lactic acidosis associated with metformin use is not greater than with other antibiotic drugs and that metformin use in patients with diabetes mellitus and HF does not necessarily increase the risk of lactic acidosis.”

Tseng studied patients with new-onset T2D enrolled in Taiwan’s National Health Insurance database. An unmatched cohort (172,542 metformin ever-users and 43,744 never-users) and propensity score-matched pair cohort (41,714 ever-users and 41,714 never-users) were followed from 2006 to 2011.

According to Tseng’s analysis, respective incidence rates of heart failure hospitalization in ever-users and never-users of metformin were 304.25 and 864.31 per 100,000 person-years, respectively, in the unmatched cohort and 469.66 and 817.01 per 100,000 person-years, respectively, in the matched cohort. A dose-response pattern was clear through the duration of metformin therapy.

Tseng said patients who took metformin saw a consistent 40% reduced risk of HF hospitalization. Benefits were most pronounced when metformin had been used for more than two and a half years.

“This population-based retrospective cohort study supports a reduced risk of hospitalization for heart failure associated with metformin use in patients with type 2 diabetes mellitus,” the author wrote. “Because metformin is inexpensive and safe and would not cause hypoglycemia when used as monotherapy, its protection against HF is worthy of more extensive investigation in both patients with diabetes mellitus and people without diabetes mellitus.”