Metformin may prolong graft survival in kidney transplant recipients (KTRs) with diabetes mellitus, new study findings suggest.

In a retrospective study of 1995 KTRs with diabetes from 6 Korean centers, 1193 were metformin users and 802 were not. Metformin use was significantly associated with a 53% lower risk of death-censored graft failure in analyses adjusted for HbA1c, metformin dose and duration, other medication use, and various relevant factors, Young Hoon Kim, MD, of the University of Ulsan College of Medicine in Seoul, Republic of Korea, and colleagues reported in the American Journal of Kidney Diseases. A higher dose of metformin correlated with lower risks of death-censored graft failure, with the lowest risk observed at a dose of 1.4 g/day. Insulin users appeared to especially benefit from metformin. The mean follow-up period was 68.2 months.

In subgroup analyses, metformin use was nonsignificantly associated with a reduced risk of death-censored graft failure and all-cause mortality in patients with pre- and post-transplantation diabetes and diabetes as the original cause of kidney failure.

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The investigators observed no cases of metformin-associated lactic acidosis, defined as a serum lactate concentration greater than 5.0 mmol/L and serum pH less than 7.35.

According to Dr Kim’s team, the study results suggest that metformin may be a preferred oral antidiabetes drug in KTRs because of its possible benefit for graft survival and low rate of metformin-associated lactic acidosis.

They noted that the number of KTRs requiring glycemic management is expected to increase.

The study lacked information on diabetes duration before transplantation and diuretic use. Data on newer antidiabetic drugs such as SGLT2 inhibitors also were limited.


Kwon S, Chul Kim Y, Kwon H, et al. Metformin use and long-term clinical outcomes in kidney transplant recipients. Am J Kid Dis. Published online March 23, 2023. doi:10.1053/j.ajkd.2023.01.446