Type 2 diabetes interferes with the body's ability to store energy from food and results in high blood sugar levels. Over time, high blood sugar levels can lead to many complications, including blindness, kidney failure, nerve damage, and cardiovascular disease (heart disease and stroke). Hemoglobin A1c is a blood test that measures blood sugar control over the previous 3 months. Lower hemoglobin A1c values mean better sugar control. Good care with diet, exercise, and medications to control blood sugar levels clearly prevents or delays the development of diabetes-related complications. Regular exercise is an important part of diabetes care and can have a very a favorable effect on blood sugar levels. However, the benefits of different types of exercise (aerobic versus resistance [weightlifting] or a combination of both) are uncertain.