Type 2 diabetes mellitus is a common disease that interferes with the body's ability to store energy from food. The pancreas makes insulin, a substance that helps store energy from food. In people with type 2 diabetes mellitus, the body makes enough insulin but cannot use it normally. The result is high blood sugar levels, which can lead to blindness, kidney failure, nerve damage, and heart disease over time. Risk factors for type 2 diabetes mellitus include being overweight, lack of exercise, and family history of the disease. Because type 2 diabetes mellitus is common and has serious complications, it is important to understand factors associated with the disease. It is known that caffeine influences the way the body handles sugar. Recent studies show that people with higher coffee intake are less likely to develop type 2 diabetes mellitus than are people with lower intake. However, these studies have largely been done in western populations and have not evaluated whether tea intake is also related to type 2 diabetes.