The causes of diabetes mellitus, including genetic factors, environmental factors, autoimmune and other common participation, the specific cause of the disease is recommended to consult a doctor. 1. Genetic factors: Genetic factors play an important role in type 1 diabetes, with more than 50 genetic variants associated with susceptibility to type 1 diabetes. type 2 diabetes is also associated with genetic factors, with more than 400 genetic variants correlating with the occurrence of type 2 diabetes. 2. Environmental factors: type 1 diabetes is mainly associated with viral infections, including rubella virus, coxsackie virus, mumps virus, etc., which damage pancreatic islet ß-cells. type 2 diabetes is mainly associated with ageing, insufficient physical activity, over-nutrition, and other poor lifestyle behaviors. 3. autoimmune factors: autoimmune factors are more prominent in type 1 diabetes, the immune cell reaction destroys the pancreatic ß-cells and reduces insulin secretion. type 1 diabetes can be detected as positive for glutamic acid decarboxylase antibody and protein complex phosphomagnesium-like protein antibody. Type 2 diabetes can be reduced or delayed by controlling poor lifestyle behaviors. Whether it is type 1 or type 2 diabetes, once diagnosed you need to take your medication as prescribed and keep your blood sugar levels under control.