Overview of Diabetes

Diabetes mellitus is a disorder resulting from absolute insulin deficiency (primary diabetes) or abnormalities in insulin secretion and function. Diabetes can also result from pancreatic disease, hormonal disorders, or genetic syndromes (secondary diabetes).

Insulin, a hormone produced in the pancreas, is essential for the body to metabolize glucose (blood sugar) to maintain the proper level of sugar in the blood and help regulate the breakdown of fats.

When glucose is not properly metabolized (broken down), too much remains in the blood and a condition called hyperglycemia results. When this occurs, the body begins to metabolize fat, resulting in increased ketone production and a disruption in the body's acid-alkaline balance (ketoacidosis). Symptoms of hyperglycemia include excessive urination and thirst, weight loss, blurry vision, and fatigue.

Causes of insulin insufficiency vary. The body may not produce enough insulin, insulin receptors may be inadequate or function improperly, or the insulin produced by the body may be defective or destroyed before it can do its job.

Primary diabetes is classified as type 1 diabetes mellitus (insulin dependent) and type 2 diabetes mellitus (non-insulin dependent).

Type 1 diabetes mellitus is most common in patients under the age of 30. It usually occurs in adolescence or childhood and is sometimes called juvenile onset diabetes. It results from the destruction of insulin-producing cells in the pancreas. Patients diagnosed with type 1 diabetes mellitus must use injected insulin to live.

Type 2 diabetes mellitus occurs most commonly in patients over the age of 30 and results from impaired insulin secretion and the decreased ability of insulin to function. While a genetic factor is involved, other factors such as obesity, excessive consumption of carbohydrates, and lack of exercise can increase the risk for type 2 diabetes mellitus. Patients with type 2 diabetes may use insulin and other drugs to help control their blood sugar, although the condition also can be controlled, at least in part, through proper diet and exercise.

Diabetes mellitus can lead to chronic complications such as cardiovascular disease, circulatory disease in the limbs, retinal disease, kidney disease, nerve damage, foot ulcers, and an increased risk for infection. For these reasons, it is critical for diabetes to be properly managed and monitored.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Jan 2001

Last Modified: 11 Sep 2015