There are two main forms of diabetes:
Type 1 Diabetes
This form of diabetes develops when the cells in the pancreas that produce insulin, known as beta cells, are destroyed. The destruction of the beta cells limits the making and release of insulin, a hormone that helps lower blood sugar. This disease can occur at any age, but the peak ages for diagnosis are in the middle teen years. There is no known way to prevent type 1 diabetes. To survive, people with type 1 diabetes must have insulin delivered by injection or pump.
Type 2 Diabetes
This form of diabetes is the most common, accounting for about 90 to 95% of diagnosed diabetes in U.S. adults. It usually begins as insulin resistance, a disorder in which cells, primarily within the muscles, liver and fat tissue, do not use insulin properly. The risk of developing type 2 diabetes is associated with aging, obesity, family history of diabetes, a personal history of gestational diabetes, not being physically active, and race and ethnicity. Schedule regular check-ups with your doctor, who will check for diabetes as part of your physical.
— Sources: Centers for Disease Control and Prevention; National Center for Chronic Disease Prevention and Health Promotion