Metformin Monotherapy Does Not Decrease AF Risk in Type 2 Diabetes

Compared with other noninsulin monotherapies, metformin as an initial treatment for type 2 diabetes (T2D) is not associated with decreased risk for atrial fibrillation (AF). These findings, from a retrospective observational study, were published in the Journal of Diabetes and Its Complications.

Patients (N=5664) who had been diagnosed with T2D and started on noninsulin monotherapies at the Cleveland Clinic between 2007 and 2017 were evaluated for AF and mortality risk.

The patients initiated metformin (n=4584) and other therapies (n=1080). The most common other therapies were sulfonylureas and thiazolidinedione.

The metformin and other therapy cohorts had a median age of 56.70 (IQR, 47.51-64.91) and 66.08 (IQR, 54.78-74.85) years (P <.001), 59.9% and 52.3% were women (P <.001), BMI was 34.25 (IQR, 29.72-39.68) and 31.71 (IQR, 27.59-37.21; P <.001), and hemoglobin A_1c was 6.50% (IQR, 6.00%-7.20%) and 6.90% (IQR, 6.20%-7.90%; P <.001), respectively.

The 10-year cumulative incidence of AF was 5.2% among the metformin recipients and 8.1% among the other therapy group.

Developing AF was associated with heart failure (hazard ratio [HR], 2.735; 95% CI, 1.624-4.61; P <.001), age (HR, 1.29; 95% CI, 1.217-1.37; P <.001), and hyperlipidemia (HR, 0.745; 95% CI, 0.573-0.97; P =.029). Metformin was not associated with AF risk (HR, 0.918; 95% CI, 0.694-1.21; P =.55).

Metformin monotherapy recipients had a lower all-cause mortality rate (1.7%) compared with the other monotherapies (5.5%; P <.05).

This study may have been limited by not using electrocardiographic data, instead relying on AF coding in the electronic medical records.

“In this observational study looking at patients with newly diagnosed T2D, first-line therapy with metformin, when compared to other non-insulin anti-hyperglycemic monotherapy, was not found to be associated with a decreased risk of developing AF,” the study authors wrote. “Given lack of concrete evidence in the literature, prospective and randomized clinical trials are imperative to reveal such protective effects of metformin and other anti-hyperglycemic agents, if exists.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.