Diabetes mellitus: epidemiology, classification, etiology and pathomechanism, diagnosis

Big picture

Diabetes mellitus is a chronic metabolic disease characterized by persistent hyperglycemia due to defective insulin secretion, defective insulin action, or both. The examiner wants you to explain three things clearly:

1. What type of diabetes is it?
2. Why is glucose high?
3. How do you prove the diagnosis?

Clinically, diabetes matters because chronic hyperglycemia damages large vessels, small vessels, nerves, kidneys, retina, and feet, while acute severe dysregulation can cause diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS).

Globally, diabetes is extremely common: the IDF Diabetes Atlas reports **589 million adults ag