Metformin use leads to excess deaths in patients with type 2 diabetes and advanced CKD a study from Taiwan confirms.

The study of 12 350 patients with type 2 diabetes and advanced CKD matched 813 metformin users in a 1:3 ratio to 2439 non-users.

Results showed adjusted mortality in metformin users was 35% higher than non-users over a median of 2·1 years. Increased mortality risk was dose-dependent and was consistent across all subgroup analyses.

The incidence of metabolic acidosis was 30% higher in metformin users than in non-users, but this difference was not significant (adjusted hazard ratio 1·30, 95% CI 0·88–1·93; p=0·19), the researchers reported in the Lancet Diabetes and Endocrinology.

The findings “give us little doubt that metformin use leads to excess deaths in patients with type 2 diabetes and advanced CKD,” wrote Kamyar Kalantar-Zadeh from the University of California Irvine School of Medicine and Connie M Rhee from UCLA Fielding School of Public Health, Los Angeles in an accompanying editorial.

The data, together with case reports, suggest that regulations restricting metformin use have probably protected many patients from lactic acidosis, hypoglycaemia, and pancreatitis, and saved thousands of lives every year, they said.

“Notwithstanding ongoing pressures from the endocrinology and nephrology communities to liberalise use of metformin in patients with CKD, the restrictions should be maintained, bearing in mind the utmost priority of practicing safe and conservative medicine,” they concluded.