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
Which of the following statements about biguanides is NOT true ? 
Select and explain. 
A. 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
C: Renal dysfunction is not a contraindication for their use
Answer: C: Renal dysfunction is not a contraindication for their use 
Explanation: None