All types of diabetes mellitus have similar symptoms and complications at advanced level. Hyperglycemia alone can lead to dehydration and ketoacidosis. Long-term complications include cardiovascular disease (double the risk), chronic renal failure (major cause of dialysis), retinal damage which can cause blindness, and nerve damage that can cause impotence and gangrene with risk of amputation. A more serious complication is more common when blood sugar control worse.

Causes
The formation of the major diabetes is due to a lack of insulin (diabetes mellitus type 1, the first known), or less sensitive tissues to insulin (diabetes mellitus type 2, a more general form). In addition, there are types of diabetes mellitus are also caused by insulin resistance that occurs in pregnant women. Type 1 requires insulin injections, while type 2 treated with oral medication and insulin needs only if the medicine is not effective. Diabetes mellitus in pregnancy usually resolves itself after delivery.

Understanding and participation of patients is very important because blood glucose levels continue to change, because the success of keeping blood sugar within normal limits may prevent the complications of diabetes. Another factor that may reduce complications are: stop smoking, optimizing cholesterol levels, maintain a stable body weight, controlling high blood pressure, and exercise regularly.