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: Medicine
[{'content': "Glycosylated haemoglobin assay is helpful in the monitoring of patients with: \nSelect and explain. \nA. Addison's disease, B. Diabetes Mellitus, C. Cushing's disease, D. Graves' disease", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]