Abstract
Biguanides have not been prescribed generally in Japan because of the lactic acidosis risk. We reevaluated the guanide metformin for efficacy and safety. Our subjects were 535 diabetic outpatients treated for 10 years with metformin. Of these, 43 had no liver injury, renal failure, or alcoholic intake but had lactate elevated at least once. Lactate and pyruvate levels in these 43 were higher than in 40 diabetic outpatients not taking metformin. The regression line ratio and slope between lactate and pyruvate in the 43 did not differ significantly from those in the 40 diabetic outpatients without metformin or from those in 58 diabetic outpatients on metformin having normal lactate concentration. The elevated lactate concentration experienced in our 43 subjects was due to elevated pyruvate, not excess acid. Our DM outpatients, to whom metformin was prescribed and who had elevated lactate concentration at least once, did not have lactic acidosis. When elevated lactate in DM outpatients taking oral metformin is evaluated, both the pyruvate level and the ratio of lactate to pyruvate must therefore be considered.
