This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Medicine
Hyperglycemia occurs after what % of beta cell mass is destroyed: 
Select and explain. 
A. 20%, B. 40%, C. 60%, D. 80%
D: 80%
Answer: D: 80% 
Explanation: * Type 1 diabetes mellitus is characterized by an inability to produce insulin endogenously. * Based on a series of histopathology studies, it is commonly stated that the onset of clinical symptoms corresponds to an 80-95% reduction in beta cell mass