Metformin ok in moderate renal disease eGFR ≥ 30 ml/min

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"Metformin ok in moderate renal disease eGFR ≥ 30 ml/min"

An editorial in a recent BMJ discusses the issue of using metformin in patients with diabetes plus renal impairment.1 Historical cautions around use were based on the risk of lactic acidosis. However, a 2008 paper from the General Practice Research database found that the risk of lactic acidosis was lower with metformin than with sulphonylureas.2 The BMJ authors point out there are risks of doing harm by not using metformin in patients with renal impairment. NICE Guidelines advise that that metformin should be stopped when eGFR reaches 30 ml/min. They imply that use at lower eGFR is something to contemplate at a secondary care level.

Patients should, however, be advised to stop metformin during periods of acute illness (such as gastrointestinal upset or other infections), where renal function may acutely deteriorate, and restart it when they have recovered.

This gem has been checked by Dr Rinki Murphy, Diabetes Specialist Greenlane and Middlemore Hospitals and Mercy Specialist Centre, 100 Mountain Rd Epsom Auckland 1023 ph (09) 623 1170, Fax: (09) 623 1172.


  1. Bodmer M, Meier C, Krahanbuhl S, Jick SS, Meier CR. Metformin, sulphonylureas or other antidiabetic drugs and the risk of lactic acidosis or hypoglycaemia. Diabetes Care 2008;31:2086-91.

Gems are chosen by the Goodfellow director Dr. Bruce Arroll to be either practice changing or practice maintaining. The information is educational and not clinical advice.

As published in NZ Doctor 13/05/2015