Lactic acidosis with phenformin therapy.

Nine cases of severe acidosis occurring in patients with maturity onset diabetes who were receiving phenformin therapy were reviewed. All had evidence of renal disease. Lactic acidosis was diagnosed by elevated blood lactate levels in seven patients, and by the clinical manifestations and laboratory information in the other two. Contributing factors are discussed, as well as means of treatment and prevention. Although the specific etiology of renal disease is not emphasized in this paper, unrecognized progressive deterioration of renal function is implicated in the etiology of lactic acidosis.