Causes of Diabetes Mellitus

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. 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. The cause of diabetes depends on the type. For all types of diabetes, the metabolism of carbohydrates (including sugars such as glucose), proteins, and fats is altered.

Type 1 diabetes can occur at any age, but it usually starts in people younger than 30. Type 1 diabetes is an autoimmune disease. An autoimmune disease results when the body's system for fighting infection-the immune system-turns against a part of the body. In diabetes, the immune system attacks and destroys the insulin-producing beta cells in the pancreas. The pancreas then produces little or no insulin. A person who has type 1 diabetes must take insulin daily to live.

The exact cause of type 1 diabetes is not known. Genetics, viruses, and autoimmune problems may play a role.Symptoms are usually severe and occur rapidly. In type 1 diabetes, the beta cells of the pancreas produce little or no insulin, the hormone that allows glucose to enter body cells. Once glucose enters a cell, it is used as fuel. Without adequate insulin, glucose builds up in the bloodstream instead of going into the cells.

The body is unable to use this glucose for energy despite high levels in the bloodstream, leading to increased hunger. In addition, the high levels of glucose in the blood causes the patient to urinate more, which in turn causes excessive thirst. Within 5 to 10 years after diagnosis, the insulin-producing beta cells of the pancreas are completely destroyed, and no more insulin is produced.

Type 2 diabetes is due primarily to lifestyle factors and genetics. Family history and genetics play a large role in type 2 diabetes. Low activity level, poor diet, and excess body weight (especially around the waist) significantly increase your risk for type 2 diabetes.

In type 2 diabetes, there also is a steady decline of beta cells that adds to the process of elevated blood sugars. Essentially, if someone is resistant to insulin, the body can, to some degree, increase production of insulin and overcome the level of resistance. After time, if production decreases and insulin cannot be released as vigorously, hyperglycemia develops.

The pancreas does not make enough insulin to keep blood glucose levels normal, often because the body does not respond well to insulin.

Other risk factors of diabetes mellitus include:

• Gestational diabetes or delivering a baby weighing more than 9 pounds
• Age over 45 years
• A parent, brother, or sister with diabetes
• Infections: Cytomegalovirus infection and Coxsackievirus B
• Some ethnic groups (particularly African Americans, Native Americans, Asians, Pacific Islanders, and Hispanic Americans)Heart disease
• High blood cholesterol level
• Polycystic ovary disease (in women)Obesity
• Not getting enough exercise
• Drugs: β-adrenergic agonists, glucocorticoids and thyroid hormone
• Previous impaired glucose tolerance