Diabetes mellitus is a condition that occurs when your blood glucose (blood sugar) is too high. Blood sugar comes from the food you eat. It is the main source of your body’s energy. Your body uses a hormone made by your pancreas called insulin to get the glucose to your body’s cells. If your body doesn’t make enough insulin or doesn’t use it well, the glucose can build up in your blood and not reach the cells. When this happens regularly, you have diabetes.

The main types of diabetes mellitus are:

  • Type 1 – an autoimmune disease where your body doesn’t make enough insulin
  • Type 2 – a condition due to insulin resistance where your body doesn’t use insulin properly
  • Gestational diabetes – diabetes that arises during pregnancy
  • Other – causes include genetic mutations, hormonal diseases, damage to the pancreas, and some medicines

Diabetes is a serious condition. Most people with type 1 and type 2 diabetes have it for the rest of their lives. If it is not treated, it can cause permanent damage. It can damage your eyes, kidneys, heart, brain, nerves, and circulation. Diabetes also raises your risk of having a heart attack or stroke. It is a common cause of blindness and lower leg amputations in the US.