This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diabetes Mellitus, Subject name: Medicine
[{'content': 'A 50 year old obese female presented with recurrent candidial urinary infection & excessive thirst. She also gives history of frequent night time urination. Which is the first test you will prefer in this patient? \nSelect and explain. \nA. HbA1c, B. Oral glucose tolerance test, C. Plasma C-peptide level, D. Random plasma glucose level', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Given clinical scenario is suggestive of Diabetes mellitus For screening, FBS or HbA1c is recommended. Because the patient has symptoms, a random plasma glucose of >200 mg/dL is adequate to diagnose diabetes mellitus. Other criteria include: FBS >126 mg/dL HbA1c>6.4% 2-hour plasma glucose >200 mg/dL during an oral glucose tolerance test C-peptide- determine normal cleavage of insulin from its precursor Normal C-peptide level with hypoglycaemia- surreptitious insulin use Low C-peptide level with hyperglycemia- pancreatic failure.', 'role': 'assistant'}]