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Metformin could benefit many more

Up to 13% of patients with type 2 diabetes who could benefit from metformin currently face an absolute contraindication because of exaggerated concern about side effects associated with renal impairment, a new study suggests.

Under new proposals only the 4% of diabetes patients with CKD stage 4 would have an absolute contraindication to metformin, But currently more than 17% are denied treatment because of fears about lactic acidosis adverse effects in those with renal impairment.

Researchers from Hull Royal Infirmary said eGFR thresholds more accurately identify patients with significant kidney disease who can safely be prescribed metformin than traditional creatinine clearance measurements.

The researchers say the relationship between metformin treatment and lactic acidosis is, at best, circumstantial, and the benefits associated with metformin treatment are so great that that current exclusions to treatment prohibit its use in too many patients.

Under the proposals, published early online in Diabetic Medicine, stage 4 chronic kidney disease (CKD) or greater would be an absolute contraindication to metformin while CKD stage 3 would alert clinicians to consider other risk factors.

Researchers drew up the suggestions after deriving eGFR measurements corresponding to current metformin creatinine limits and applying them to 12,482 patients with type 2 diabetes.

They found that while many patients are currently barred from receiving metformin (21.8 percent of men and 13.5 per cent of women), far fewer have CKD stage 4 (3.3 per cent of men and 4.7 per cent of women).

Instead 20.8 per cent of men and 28.1 per cent of women had CKD stage 3.

Men in particular were much more likely to be denied metformin using creatinine cut-offs, rather than eGFR thresholds.

Lead author Professor Eric Kilpatrick, consultant chemical pathologist, said: This is not because their renal function is necessarily poorer, but because they have a greater muscle mass which, in turn, leads to higher creatinine concentrations in the blood.

Moving over to eGFR limits should help correct this imbalance.

More than 17% of patients denied treatment with Metformin because of fears about lactic acidosis adverse effects More than 17% of patients denied treatment with Metformin because of fears about lactic acidosis adverse effects

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