Diabetes : Overview, Causes, & Risk Factors

Definition

Diabetes is a chronic (lifelong) disease marked by high levels of sugar in the blood.

See also:

  • Gestational diabetes
  • Type 1 diabetes
  • Type 2 diabetes
  • Metabolic syndrome

Overview, Causes, & Risk Factors

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.

To understand diabetes, it is important to first understand the normal process by which food is broken down and used by the body for energy. Several things happen when food is digested:

  • A sugar called glucose enters the bloodstream. Glucose is a source of fuel for the body.
  • An organ called the pancreas makes insulin. The role of insulin is to move glucose from the bloodstream into muscle, fat, and liver cells, where it can be used as fuel.

People with diabetes have high blood sugar. This is because:

  • Their pancreas does not make enough insulin
  • Their muscle, fat, and liver cells do not respond to insulin normally
  • Both of the above

There are three major types of diabetes:

  • Type 1 diabetes is usually diagnosed in childhood. Many patients are diagnosed when they are older than age 20. In this disease, the body makes little or no insulin. Daily injections of insulin are needed. The exact cause is unknown. Genetics, viruses, and autoimmune problems may play a role.
  • Type 2 diabetes is far more common than type 1. It makes up most of diabetes cases. It usually occurs in adulthood, but young people are increasingly being diagnosed with this disease. The pancreas does not make enough insulin to keep blood glucose levels normal, often because the body does not respond well to insulin. Many people with type 2 diabetes do not know they have it, although it is a serious condition. Type 2 diabetes is becoming more common due to increasing obesity and failure to exercise.
  • Gestational diabetes is high blood glucose that develops at any time during pregnancy in a woman who does not have diabetes. Women who have gestational diabetes are at high risk of type 2 diabetes and cardiovascular disease later in life.

Diabetes affects more than 20 million Americans. Over 40 million Americans have prediabetes (early type 2 diabetes).

There are many risk factors for type 2 diabetes, including:

  • Age over 45 years
  • A parent, brother, or sister with diabetes
  • Gestational diabetes or delivering a baby weighing more than 9 pounds
  • Heart disease
  • High blood cholesterol level
  • Obesity
  • Not getting enough exercise
  • Polycystic ovary disease (in women)
  • Previous impaired glucose tolerance
  • Some ethnic groups (particularly African Americans, Native Americans, Asians, Pacific Islanders, and Hispanic Americans)

Pictures & Images

Endocrine glands

Endocrine glands release hormones (chemical messengers) into the bloodstream to be transported to various organs and tissues throughout the body. For instance, the pancreas secretes insulin, which allows the body to regulate levels of sugar in the blood. The thyroid gets instructions from the pituitary to secrete hormones which determine the pace of chemical activity in the body (the more hormone in the bloodstream, the faster the chemical activity; the less hormone, the slower the activity).

Diabetic retinopathy

Diabetic retinopathy
Diabetes causes an excessive amount of glucose to remain in the blood stream which may cause damage to the blood vessels. Within the eye the damaged vessels may leak blood and fluid into the surrounding tissues and cause vision problems.

Islets of Langerhans

Islets of Langerhans

Islets of Langerhans contain beta cells and are located within the pancreas. Beta cells produce insulin which is needed to metabolize glucose within the body.

Blood test

Blood test

To monitor the amount of glucose within the blood a person with diabetes should test their blood regularly. The procedure is quite simple and can often be done at home.

Pancreas

Pancreas
The pancreas is located behind the liver and is where the hormone insulin is produced. Insulin is used by the body to store and utilize glucose.

Insulin pump

Insulin pump

Various styles of insulin pumps may be utilized by people with diabetes to inject insulin into the body in a controlled, more convenient and discreet manner.

Glucose test

Glucose test

A person with diabetes constantly manages their blood’s sugar (glucose) levels. After a blood sample is taken and tested, it is determined whether the glucose levels are low or high. If glucose levels are too low carbohydrates are ingested.�If glucose in the blood is too high, the appropriate amount of insulin is administered into the body such as through an insulin pump.

Insulin pump

Insulin pump

The catheter at the end of the insulin pump is inserted through a needle into the abdominal fat of a person with diabetes. Dosage instructions are entered into the pump’s small computer and the appropriate amount of insulin is then injected into the body in a calculated, controlled manner.

Type I diabetes

Type I diabetes

In response to high levels of glucose in the blood, the insulin-producing cells in the pancreas secrete the hormone insulin. Type I diabetes occurs when these cells are destroyed by the body�s own immune system.

Diabetic blood circulation in foot

Diabetic blood circulation in foot

People with diabetes are at risk for blood vessel injury, which may be severe enough to cause tissue damage in the legs and feet.

Food and insulin release

Food and insulin release

Insulin is a hormone secreted by the pancreas in response to increased glucose levels in the blood.

Insulin production and diabetes

Insulin production and diabetes

Insulin is a hormone produced by the pancreas that is necessary for cells to be able to use blood sugar.

Monitor blood glucose – series
Part 1

Monitor blood glucose - series : Part 1

Set up the meter according to the specific directions that come with your meter. Get the supplies ready, including a new test strip and disposable lancet. Place the lancet into the lancing device.


Review Date : 5/20/2009
Reviewed By : Reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Also reviewed by Deborah Wexler, MD, Assistant Professor of Medicine, Harvard Medical School, Endocrinologist, Massachusetts General Hospital.

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