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
Metformin is NOT effective in lowering of blood sugar level in which of the following patients ? 
Select and explain. 
A. Non diabetics, B. Obese diabetics, C. Type 2 diabetics, D. Diabetics not responding to sulfonylureas
A: Non diabetics
Answer: A: Non diabetics 
Explanation: None