Diabetes is a complex group of diseases with a variety of causes. People with diabetes have high blood glucose, also called high blood sugar or hyperglycemia.
                
Diabetes is a disorder of metabolismthe way the body uses digested food for energy. The digestive tract breaks down carbohydratessugars and starches found in many foodsinto glucose, a form of sugar that enters the bloodstream. With the help of the hormone insulin, cells throughout the body absorb glucose and use it for energy. Insulin is made in the pancreas, an organ located behind the stomach. As the blood glucose level rises after a meal, the pancreas is triggered to release insulin. Within the pancreas, clusters of cells called islets contain beta cells, which make the insulin and release it into the blood.
                
Diabetes develops when the body doesnt make enough insulin or is not able to use insulin effectively, or both. As a result, glucose builds up in the blood instead of being absorbed by cells in the body. The bodys cells are then starved of energy despite high blood glucose levels.
                
Over time, high blood glucose damages nerves and blood vessels, leading to complications such as heart disease, stroke, kidney disease, blindness, dental disease, and amputations. Other complications of diabetes may include increased susceptibility to other diseases, loss of mobility with aging, depression, and pregnancy problems.
                
Main Types of Diabetes
                
The three main types of diabetes are type 1, type 2, and gestational diabetes:
                
- Type 1 diabetes, formerly called juvenile diabetes, is usually first diagnosed in children, teenagers, and young adults. In this type of diabetes, the beta cells of the pancreas no longer make insulin because the bodys immune system has attacked and destroyed them.  - Type 2 diabetes, formerly called adult-onset diabetes, is the most common type of diabetes. About 90 to 95 percent of people with diabetes have type 2.1 People can develop type 2 diabetes at any age, even during childhood, but this type of diabetes is most often associated with older age. Type 2 diabetes is also associated with excess weight, physical inactivity, family history of diabetes, previous history of gestational diabetes, and certain ethnicities.   Type 2 diabetes usually begins with insulin resistance, a condition linked to excess weight in which muscle, liver, and fat cells do not use insulin properly. As a result, the body needs more insulin to help glucose enter cells to be used for energy. At first, the pancreas keeps up with the added demand by producing more insulin. But in time, the pancreas loses its ability to produce enough insulin in response to meals, and blood glucose levels rise.  - Gestational diabetes is a type of diabetes that develops only during pregnancy.  The hormones produced during pregnancy increase the amount of insulin needed to control blood glucose levels. If the body cant meet this increased need for insulin, women can develop gestational diabetes during the late stages of pregnancy.  Gestational diabetes usually goes away after the baby is born. Shortly after pregnancy, 5 to 10 percent of women with gestational diabetes continue to have high blood glucose levels and are diagnosed as having diabetes, usually type 2.1 Research has shown that lifestyle changes and the diabetes medication, metformin, can reduce or delay the risk of type 2 diabetes in these women. Babies born to mothers who had gestational diabetes are also more likely to develop obesity and type 2 diabetes as they grow up.  More information about gestational diabetes is provided in the NIDDK health topic, What I need to know about Gestational Diabetes,or by calling 18008608747.
                
Other Types of Diabetes
                
Many other types of diabetes exist, and a person can exhibit characteristics of more than one type. For example, in latent autoimmune diabetes in adults, people show signs of both type 1 and type 2 diabetes. Other types of diabetes include those caused by genetic defects, diseases of the pancreas, excess amounts of certain hormones resulting from some medical conditions, medications that reduce insulin action, chemicals that destroy beta cells, infections, rare autoimmune disorders, and genetic syndromes associated with diabetes.
                
More information about other types of diabetes is provided in the NIDDK health topic, Causes of Diabetes, or by calling 18008608747.