Which of the following antidiabetic drugs can cause vitamin B12 deficiency?: (A) Glipizide, (B) Acarbose, (C) Metformin, (D) Pioglitazone
Answer is C. Lactic acidosis (more with phenformin) and megaloblastic anemia (more with metformin) due to vitamin B12 defi­ciency are the major adverse effects of these drugs. Lactic acidosis is more likely to occur in the presence of hepatic and renal impairment or alcohol ingestion.