Type 2 diabetes mellitus interferes with the body's ability to use insulin, a substance created by the pancreas to store energy from food. In people with type 2 diabetes, the body makes plenty of insulin but can't use it normally. The result is high blood sugar levels. Over time, high blood sugar can lead to complications, including kidney problems. Diabetes is the most common cause of kidney failure in the United States. Good control of blood sugar and blood pressure delays the development of kidney problems in people with type 2 diabetes. Blood pressure drugs called angiotensin-converting enzyme inhibitors also protect people with type 2 diabetes against kidney problems. This benefit occurs whether or not people also have high blood pressure. Another type of blood pressure drug called angiotensin-receptor antagonists (AR antagonists) protects against kidney problems in people who have both type 2 diabetes and high blood pressure. However, we don't know if AR antagonists protect the kidneys in people with type 2 diabetes and normal blood pressure.