Metformin is used to lower blood sugar in people with type 2 diabetes. Because this drug is removed from the body by the kidneys, it is not given to patients with poor kidney function. A systematic review published in the Journal of the American Medical Association (JAMA) by authors from Aston University, Yale University and Texas Southwestern Medical Center has reassessed the evidence. The authors conclude that appropriate dose adjustment and monitoring of kidney function allow metformin to be used for patients with moderate kidney disease. This opens up the potential benefits of metformin to about one third of patients with type 2 diabetes in whom kidney function becomes impaired. The results of the study support guidance already offered in the UK by the National Institute for Health and Care Excellence (NICE).
Professor Cliff Bailey from Aston University said: “Increasing experience with metformin supports the recommendation of NICE to continue use of the drug when kidney function declines, provided that the dose is reduced and kidney function is closely monitored.” He added “But it is still very important to stop metformin if kidney function becomes severely impaired or if other problems arise such as serious infection or serious heart, lung or liver conditions.”
When kidney function deteriorates metformin can accumulate in the body. This increases the risk of lactic acidosis, a rare but potentially dangerous condition of excess lactate and high acidity of the blood. The new JAMA review assessed the risk of lactic acidosis with metformin in diabetes patients at different stages of impaired kidney function. The risk was extremely low and was generally indistinguishable from the risk in people with diabetes who were receiving other treatments. The authors conclude that available evidence supports cautious use of metformin in patients with mild-to-moderate kidney disease if the dose is reduced and kidney function is adequately monitored.
Note for editors
Type 2 diabetes affects about 6% of adults in the UK. About one third of these patients develop chronic kidney disease. Metformin is usually the preferred initial treatment to lower blood sugar levels in type 2 diabetes. Metformin has the added advantages of avoiding extra weight gain, avoiding dangerous falls in blood sugar (so-called hypos), and helping to protect against cardiovascular diseases and other complications of type 2 diabetes. Because metformin is removed from the body by the kidneys it should not be used in patients with advanced kidney disease. The new review in JAMA examines the evidence for use of metformin in type 2 diabetes patients with mild-to-moderate kidney disease. The conclusions support guidance by the National Institute for Health and Care Excellence (NICE) allowing metformin to be used with caution in type 2 diabetes patients with moderate kidney disease if the drug dose is reduced and kidney function is closely monitored.
The reference for this review is:
Inzucchi SE, Lipska KJ, Mayo H, Bailey CJ and McGuire DK. Metformin in patients with type 2diabetes and kidney disease. JAMA 2014, 312: doi: 10.1001/jama.2014.15298
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