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: Dental
The sixth complication of diabetes mellitus is 
Select and explain. 
A. Retinopathy, B. Rental failure, C. Ischemic heart diseases, D. Periodontitis
D: Periodontitis
Answer: D: Periodontitis 
Explanation: None