- Impaired renal function defined as serum-creatinine = 125 µmol/l (= 1.4 mg/dl) for males and = 110 µmol/L (= 1.3 mg/dl) for females or according to local label for metformin [For France: glomerular filtration rate below 60 ml/min, calculated by the Cockroft & Gault formula] at end of treatment in NN1250-3643.