Diabetes is a disease that is characterized by high blood sugar levels. This happens when your body can't make or use insulin properly. Diabetes can lead to heart disease, stroke, nerve damage, and kidney failure if it's not managed well. There are three types of diabetes: type 1, type 2, and gestational diabetes. Type 1 diabetes is an autoimmune disease in which the body's immune system attacks and destroys the cells that produce insulin. Type 2 diabetes is the most common type of diabetes. It develops when the body can't use insulin properly or makes too little insulin. Gestational diabetes develops in some women during pregnancy. There is no cure for diabetes, but it can be managed with medication, diet, and exercise.