This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diabites & Inappropriate Antidiuretic Hormone, Subject name: Medicine
Diabetes mellitus diagnosed when? 
Select and explain. 
A. Fasting blood glucose is 100 and post prandial 140, B. Fasting blood sugar 125 and 2 hour postprandial blood sugar is 199, C. Insulin level, D. Hb A1c > 6.5%
D: Hb A1c > 6.5%
Answer: D: Hb A1c > 6.5% 
Explanation: Ans. is 'd' i.e., Hba1c > 6.5%