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: Pathology
A 50-year-old obese man complains of several recent
abscesses in the gingiva with loosening of teeth. He
also suffers from itching of skin and polyuria. The most
probable etiology is: 
Select and explain. 
A. Scurvy, B. Myxoedema, C. Diabetes mellitus, D. Vitamin A deficiency
C: Diabetes mellitus
Answer: C: Diabetes mellitus 
Explanation: None