Type 2 diabetes mellitus interferes with the body's ability to store energy from food. The pancreas makes insulin, a substance that helps to store energy from food. In people with type 2 diabetes, the body makes plenty of insulin but cannot use it normally. The result is high blood sugar levels, and over time, high blood sugar can lead to blindness, kidney failure, and nerve damage. Diabetes increases the rate of atherosclerosis (hardening of the arteries), a condition that can lead to heart disease. Being overweight, lack of exercise, and family history of the disease increase the likelihood of developing type 2 diabetes. Nearly 8% of U.S. adults age 20 years and older have diabetes. Many others have an increased likelihood of developing diabetes.