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 genetics and environmental factors, such as excess weight and inactivity, seem to be contributing factors.
How insulin works
Insulin is a hormone that comes from the gland situated behind and below the stomach (pancreas).
- 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 glucose 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 doesn't work well. Instead of moving into your cells, sugar builds up in your bloodstream. As blood sugar levels increase, the insulin-producing beta cells in the pancreas produce more insulin, but eventually these cells become impaired and can't make enough insulin to meet the body's demands.
In the much less common type 1 diabetes, the immune system destroys the beta cells, leaving the body with little to no insulin.
Jul. 24, 2014
- Diabetes mellitus (DM). The Merck Manuals: The Merck Manual for Health Care Professionals. http://www.merckmanuals.com/professional/endocrine_and_metabolic_disorders/diabetes_mellitus_and_disorders_of_carbohydrate_metabolism/diabetes_mellitus_dm.html. Accessed April 29, 2014.
- Papadakis MA, ed., et al. Current Medical Diagnosis & Treatment 2014. 53rd ed. New York, N.Y.: The McGraw-Hill Companies; 2014. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=1. Accessed April 27, 2014.
- Standards of medical care in diabetes — 2014. Diabetes Care. 2014;37:s14.
- What are my options? American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/medication/oral-medications/what-are-my-options.html. Accessed May 10, 2014.
- McKulloch DK. Initial management of blood glucose in adults with type 2 diabetes mellitus. http://www.uptodate.com/home. Accessed May 10, 2014.
- Hyperglycemia (High blood glucose). American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hyperglycemia.html. Accessed April 29, 2014.
- DKA (ketoacidosis) and ketones. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/complications/ketoacidosis-dka.html. Accessed April 29, 2014.
- Natural medicines in the clinical management of diabetes. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed May 10, 2014.
- Gardner DG, et al. Greenspan's Basic & Clinical Endocrinology. 9th ed. New York, N.Y.: The McGraw-Hill Companies; 2011. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=13. Accessed April 27, 2014.
You Are ... The Campaign for Mayo Clinic
Mayo Clinic is a not-for-profit organization. Make a difference today.