Diabetes Overview
Learn about diabetes symptoms, causes & treatments.

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What Is Diabetes?

Diabetes is a common group of chronic metabolic diseases that cause high blood sugar (glucose) levels in the body due to defects in insulin product

What Is Diabetes?

Diabetes is a common group of chronic metabolic diseases that cause high blood sugar (glucose) levels in the body due to defects in insulin production or function. Diabetes is also known as diabetes mellitus to distinguish it from a relatively rare metabolic disorder called diabetes insipidus that doesn’t affect blood sugar. Symptoms of diabetes occur when a lack of insulin or insulin resistance stops glucose from entering the cells and fueling and energizing the body. The resulting spike in glucose can result in symptoms such as increased hunger and thirst, weight loss, fatigue, and frequent infections. Long-term complications include kidney failure, nerve damage, and blindness.

Types of Diabetes

Diabetes is categorized into two main categories and one subcategory, but all are typified by problems of insulin resulting in high blood sugar levels in the body. The categories are:

Type 1 Diabetes

This type of diabetes is categorized as an autoimmune disease and occurs when the body’s misdirected immune system attacks and destroys insulin-producing beta cells in the pancreas. Although genetic or environmental triggers are suspected, the exact cause of type 1 diabetes—once referred to as insulin-dependent or juvenile-onset diabetes—is not completely understood. Type 1 accounts for only five to 10 percent of diabetes cases in the United States, and while it can occur at any age, most patients are diagnosed as children or young adults. Those with type 1 diabetes must take insulin daily to manage their condition.

Type 2 Diabetes

This type most often develops gradually with age and is characterized by insulin resistance in the body. Because of this resistance, the body’s fat, liver, and muscle cells are unable to take in and store glucose, which is used for energy. The glucose remains in the blood. The abnormal buildup of glucose (blood sugar) can result in hyperglycemia and impaired body functions. Type 2 diabetes occurs most often in people who are overweight because fat interferes with the body’s ability to use insulin, but it also can occur in thin people and the elderly. Family history and genetics play a major role in type 2 diabetes, and inactivity and poor diet can also increase the risk.

Gestational Diabetes

Gestational diabetes is defined as blood-sugar elevation during pregnancy and is known to affect about three to eight percent of women. Left undiagnosed or untreated, it can lead to problems such as high birth weight and breathing problems for the baby. Gestational diabetes usually resolves in the mother after the baby is born, but statistics show that women who have gestational diabetes have a much greater chance of developing type 2 diabetes within five to 10 years.

Prediabetes

This condition is marked by blood sugar levels that are too high to be considered normal but are not yet high enough to be in the range of a typical diabetes diagnosis. Prediabetes increases not only your risk of developing diabetes but also heart disease. 

Written by: the Healthline Editorial Team
Edited by:
Medically Reviewed by: Eric Steinmehl
Published: Aug 25, 2010
Last Updated: Apr 7, 2014
Published By: Healthline Networks, Inc.
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