Insulin is a hormone produced by the pancreas to control blood sugar. Diabetes can be caused by too little insulin, resistance to insulin, or both.
To understand diabetes, it is important to first understand the normal process by which food is broken down and used by the body for energy. Several things happen when food is digested:
A sugar called glucose enters the bloodstream. Glucose is a source of fuel for the body.
An organ called the pancreas makes insulin. The role of insulin is to move glucose from the bloodstream into muscle, fat, and liver cells, where it can be used as fuel.
People with diabetes have high blood sugar because their body cannot move sugar into fat, liver, and muscle cells to be stored for energy. This is because either:
Their pancreas does not make enough insulin
Their cells do not respond to insulin normally
Both of the above
There are three major types of diabetes. The causes and risk factors are different for each type:
Type 1 diabetes can occur at any age, but it is most often diagnosed in children, teens, or young adults. In this disease, the body makes little or no insulin. Daily injections of insulin are needed. The exact cause is unknown.
Type 2 diabetes makes up most of diabetes cases. It most often occurs in adulthood, but teens and young adults are now being diagnosed with it because of high obesity rates. Many people with type 2 diabetes do not know they have it.
Gestational diabetes is high blood sugar that develops at any time during pregnancy in a woman who does not have diabetes.
Diabetes affects more than 20 million Americans. Over 40 million Americans have pre-diabetes (early type 2 diabetes).
High blood sugar levels can cause several symptoms, including:
Because type 2 diabetes develops slowly, some people with high blood sugar have no symptoms.
Symptoms of type 1 diabetes develop over a short period of time. People may be very sick by the time they are diagnosed.
Signs and tests
A urine analysis may be used to look for high blood sugar. However, a urine test alone does not diagnose diabetes.
Your health care provider may suspect that you have diabetes if your blood sugar level is higher than 200 mg/dL. To confirm the diagnosis, one or more of the following tests must be done.
Fasting blood glucose level -- diabetes is diagnosed if it is higher than 126 mg/dL twice. Levels between 100 and 126 mg/dL are called impaired fasting glucose or pre-diabetes. These levels are risk factors for type 2 diabetes.
Studies have shown that better control of blood sugar, cholesterol, and blood pressure levels in persons with diabetes helps reduce the risk of kidney disease, eye disease, nervous system disease, heart attack, and stroke.
Because of nerve damage, you could have problems digesting the food you eat. You could feel weakness or have trouble going to the bathroom. Nerve damage can also make it harder for men to have an erection.
High blood sugar and other problems can lead to kidney damage. The kidneys might not work as well, and they may even stop working.
Keeping an ideal body weight and an active lifestyle may prevent type 2 diabetes.
There is no way to prevent type 1 diabetes.
To prevent complications of diabetes, visit your health care provider or diabetes educator at least four times a year. Talk about any problems you are having.
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Eisenbarth GS, Polonsky KS, Buse JB. Type 1 Diabetes Mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 31.
A.D.A.M. Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Ari S. Eckman, MD, Chief, Division of Endocrinology, Diabetes, and Metabolism, Trinitas Regional Medical Center, Elizabeth, NJ. Review provided by VeriMed Healthcare Network (6/28/2011).