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Causes

By Mayo Clinic staff

Controlling Your Diabetes

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Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas stops producing enough insulin. Exactly why this happens is unknown, although excess weight and inactivity seem to be contributing factors.

How insulin works
Insulin is a hormone that comes from the pancreas, a gland situated behind and below the stomach.

  • The pancreas secretes insulin into the bloodstream.
  • The insulin circulates, enabling sugar to enter your cells.
  • Insulin lowers the amount of sugar in your bloodstream.
  • As your blood sugar level drops, so does the secretion of insulin from your pancreas.

The role of glucose
Glucose — a sugar — is a main source of energy for the cells that make up muscles and other tissues.

  • Glucose comes from two major sources: food and your liver.
  • Sugar is absorbed into the bloodstream, where it enters cells with the help of insulin.
  • Your liver stores and makes glucose.
  • When your insulin levels are low, such as when you haven't eaten in a while, the liver breaks down stored glycogen into glucose to keep your glucose level within a normal range.

In type 2 diabetes, this process works improperly. Instead of moving into your cells, sugar builds up in your bloodstream.

In the much less common type 1 diabetes, the pancreas produces little or no insulin.

Risk factors Symptoms
References
  1. Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=4. Accessed Sept. 23, 2012.
  2. Diabetes mellitus (DM). The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec12/ch158/ch158b.html#sec12-ch158-ch158b-1105. Accessed Sept. 30, 2012.
  3. Inzucchi SE, et al. Management of hyperglycemia in type 2 diabetes: A patient-centered approach. Diabetes Care. 2012;35:1364.
  4. Standards of medical care in diabetes — 2013. Diabetes Care. 2013:36:S1.
  5. Bonoro E, et al. The pros and cons of diagnosing diabetes with A1C. Diabetes Care. 2011;34:S184.
  6. Your guide to diabetes: Type 1 and type 2. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/type1and2/index.htm. Accessed Sept. 23, 2012.
  7. Screening for type 2 diabetes mellitus in adults. U.S. Preventive Services Task Force. http://www.uspreventiveservicestaskforce.org/uspstf08/type2/type2rs.htm. Accessed Sept. 23, 2012.
  8. Diabetes statistics. American Diabetes Association. http://www.diabetes.org/diabetes-basics/diabetes-statistics. Accessed Sept. 23, 2012.
  9. What people with diabetes need to know about osteoporosis. National Institute of Arthritis and Musculoskeletal and Skin Diseases. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Conditions_Behaviors/diabetes.asp. Sept. 23, 2011.
  10. Mazzola N. Review of current and emerging therapies in type 2 diabetes mellitus. American Journal of Managed Care. 2012;18:S17.
  11. Take charge of your diabetes. Centers for Disease Control and Prevention. http://www.cdc.gov/diabetes/pubs/tcyd/vaccin.htm. Accessed Sept. 30, 2012.
  12. Hyperosmolar hyperglycemic nonketotic syndrome (HHNS). American Diabetes Association. http://www.diabetes.org/living-with-diabetes/complications/hyperosmolar-hyperglycemic.html. Accessed Sept. 19, 2012.
  13. Dixon JB, et al. Bariatric surgery: An IDF statement for obese type 2 diabetes. Arquivos Brasileiros de Endocrinologia & Metabologia. 2011;55:367.
  14. Before pregnancy. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/complications/pregnant-women/before-pregnancy.html. Accessed Sept. 30, 2012.
  15. Helzner EP, et al. Contribution of vascular risk factors to the progression in Alzheimer disease. Archives of Neurology. 2009;66:343.
  16. Bainbridge KE. Diabetes and hearing impairment in the United States: Audiometric evidence from the National Health and Nutrition Examination Survey, 1999 to 2004. Annals of Internal Medicine. 2008;149:1.
  17. Schauer PR, et al. Bariatric surgery vs. intense medical therapy in obese patients with diabetes. New England Journal of Medicine. 2012;366:1567.
  18. Mingrone G, et al. Bariatric surgery vs. conventional medical therapy for type 2 diabetes. New England Journal of Medicine. 2012;366:1577.
  19. A1C. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c/?keymatch=a1c. Accessed Oct. 1, 2012.
DS00585 Jan. 25, 2013

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