Metformin Shows Benefits after Kidney Transplant

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Treatment with metformin may reduce the risk of graft failure and death in diabetic kidney transplant recipients (KTRs), reports a study in the American Journal of Kidney Diseases.

The retrospective analysis included 1995 patients with type 2 diabetes who underwent kidney transplantation at six centers in the Republic of Korea from 2000 through 2019. Of these, 1193 patients used metformin for longer than 90 days after kidney transplant; 802 patients did not receive metformin. The two groups were compared for all-cause mortality and death-censored graft failure (DCGF), with biopsy-proven acute rejection (BPAR) and lactic acidosis events as secondary outcomes. Analyses accounted for the impact of changes in metformin dose and hemoglobin A1c over time.

There were some differences in patient characteristics: 3 months after transplantation, metformin-treated KTRs had better kidney function but poorer glycemic control. During a mean follow-up of 65 months, 5.1% had graft failure. Patients using metformin had lower DCGF (adjusted hazard ratio, 0.47 on a fully adjusted analysis). Metformin was associated with lower DCGF and all-cause mortality for patients with pre-transplant and post-transplant diabetes.

Among KTRs with post-transplant diabetes, metformin was associated with a lower risk of BPAR, although this difference was not significant in the fully adjusted analysis. There were no confirmed cases of metformin-associated lactic acidosis. Among metformin users, those receiving higher doses had lower rates of DCGF and BPAR.

Metformin is increasingly recommended for patients with advanced chronic kidney disease, based on evidence of a survival benefit and renal protective effect with a low risk of lactic acidosis. Few studies have evaluated the use of metformin in KTRs with pre-transplant or post-transplant diabetes.

This retrospective study shows a reduced risk of DCGF in diabetic KTRs treated with metformin, with no evidence of lactic acidosis. The benefits may be greater in patients receiving higher metformin doses. The researchers call for randomized trials to validate their findings [Kwon S, et al. Metformin use and long-term clinical outcomes in kidney transplant recipients. Am J Kidney Dis, published online ahead of print March 23, 2023. doi: 10.1053/j.ajkd.2023.01.446;].