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 statements about biguanides is NOT true ? \nSelect and explain. \nA. Do not stimulate insulin release, B. Decrease hepatic glucose production, C. Renal dysfunction is not a contraindication for their use, D. Can be combined with sulfonylureas', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]