This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
Which of the following anti diabetic drugs can cause vitamin B12 deficiency 
Select and explain. 
A. Glipizide, B. Acarbose, C. Metformin, D. Pioglitazone
C: Metformin
Answer: C: Metformin 
Explanation: Refer Goodman Gilman 12/e p 1259 Lactic acidosis and Megaloblastic anemia 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