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Type 1 Diabetes Mellitus

What Is It? & Symptoms

Monday, Aug. 27, 2007; 7:47 PM

Copyright Harvard Health Publications 2007

What Is It?

Table of Contents

Diabetes mellitus, commonly called just diabetes, is a disease in which the body cannot process or use the energy-giving nutrients in foods.

During digestion, food is broken down into basic components, such as fats, amino acids from proteins, and simple sugars from carbohydrates. All of these nutrients can be processed by the liver into one type of simple sugar, glucose, which then enters the bloodstream. Glucose, the body's main source of energy, enters body cells with the help of a hormone called insulin, which acts somewhat like a gatekeeper. Without insulin, which is made by the pancreas, glucose cannot pass through the cell wall, and the cell "starves."

In diabetes, not enough insulin is available to move glucose into the cells, either because too little insulin is being made or because the cells cannot respond to insulin. Because glucose cannot enter cells, it stays in the blood, which is why people with diabetes have high blood sugar. With too much glucose in the blood and not enough in the cells, the body has to work harder to keep functioning, and organs and bodily systems can suffer severe damage.

There are three types of diabetes: type 1 diabetes, type 2 diabetes and gestational diabetes. In type 1 diabetes, also called insulin-dependent diabetes or juvenile diabetes, some or all of the insulin-producing cells of the pancreas are destroyed, leaving the patient with little or no naturally produced insulin. Only about 5% to 10% of people with diabetes have type 1. The most common type of diabetes is type 2, in which the pancreas makes insulin but the cells in the body do not respond to it (are insulin-resistant). In gestational diabetes, certain pregnancy-related hormones make the body resistant to insulin.

Diabetes affects more than just blood sugar. If cells cannot use glucose for energy, they have to use something else. In an effort to provide alternative fuels for the body, the liver produces acidic substances called ketones, which build up in the blood. When ketones are made in large quantities, the blood becomes abnormally acidic. This creates a severe, potentially life-threatening condition called ketoacidosis, which can cause heart problems and affect the nervous system to the point of coma or death.

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