[A case of lactic acidosis caused by buformin in an oldest elderly diabetic patient].

A 93-year-old male was urgently admitted to our hospital with dyspnea and disturbance of consciousness. The patient had been visiting a general physician regularly for ten years, for treatment of type 2 diabetes. He had been treated with glibenclamide and voglibose, until voglibose was replaced with buformin 3 months before admission. During pre-admission treatment, his HbA1c was 10-12% and serum Cr level was around 2mg/dL, but insulin therapy had never been considered because of "being too old". The patient had started taking furosemide one year before admission, because of edema of the lower legs, and also spironolactone two months before admission. Anorexia had continued for one month before admission on May 29, 2003. On admission, his laboratory data were; blood glucose 87mg/dL, HbA1c 12.5%, BUN 75mg/dL, Cr 3.9mg/dL, lactate 253.1 mg/dL, and blood gas analysis; pH 6.97, anion gap 45.3mmol/L breathing room air, suggesting marked lactic acidosis with renal failure. Intensive care with bicarbonate and fluid therapy was successful, and his glycemic control improved markedly with insulin. On the other hand, his activity of daily living (ADL) severely deteriorated while in hospital Home follow-up was therefore not indicated, and he had to change a hospital for further follow-up. This case report gives rise to the question of how we should manage diabetes in the oldest elderly, including the use of insulin and biguanides. In addition, complications of biguanides in the elderly are reviewed.