This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Which of the following antidiabetic drugs can cause vitamin B12 deficiency? \nSelect and explain. \nA. Glipizide, B. Acarbose, C. Metformin, D. Pioglitazone', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Lactic acidosis (more with phenformin) and megaloblastic anemia (more with metformin) due to vitamin B12 defi\xadciency 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.', 'role': 'assistant'}]