Overview of Diabetes Mellitus

Many people think of diabetes as the "sugar disease." But that's only part of the story. Diabetes mellitus, more commonly referred to simply as diabetes, is a chronic disease in which high levels of glucose (sugar) build up in the bloodstream. The term "diabetes" is derived from the Greek word for siphon (a tube bent in two through which liquid flows) and the Latin word "mellitus," which means sweet as honey.

What Is Diabetes?

The disease is aptly named: Persistent thirst and frequent passing of urine containing glucose are characteristic symptoms of diabetes. These symptoms result from insufficient production of insulin by the pancreas or resistance of the body’s tissues to insulin action—or a combination of both. To understand what this means, you have to know where your body's glucose comes from, what it's used for, and how it is regulated by insulin.

What Is Glucose?

Glucose is a sugar serving as the fuel that provides energy for the body's cells. Your liver produces some glucose and your body gets the rest by digesting sugars, starches, and other foods you eat.

What Is Insulin?

Insulin is a hormone produced by beta cells in a part of the pancreas known as the islets of Langerhans. Insulin controls how much glucose the liver produces and also helps to move glucose from the bloodstream into your cells, where it is needed as a source of energy.

The uptake of glucose into your cells occurs through a complex series of events. It begins when insulin attaches ("binds") to receptor sites on the surface of cells in muscles and other tissues and causes carrier proteins (called glucose transporters) to move from inside the cell to the cell's surface. Like little dump trucks, these transport proteins deliver glucose from outside the cell to the inside. Without the initial binding of insulin to the receptor sites, glucose enters the cells too slowly.

Publication Review By: Written by: Christopher D. Saudek, M.D.; Simeon Margolis, M.D., Ph.D.

Published: 20 Apr 2009

Last Modified: 03 Apr 2013