Diseases and Conditions
Type 1 diabetes
Overview
Symptoms
Causes
Risk factors
Complications
Prevention
Diagnosis
Treatment
Lifestyle and home remedies
Coping and support
Preparing for an appointment
Causes
The exact cause of type 1 diabetes is unknown. Usually, the body's own immune system — which normally fights harmful bacteria and viruses — mistakenly destroys the insulin-producing (islet, or islets of Langerhans) cells in the pancreas. Other possible causes include:
- Genetics
- Exposure to viruses and other environmental factors
The role of insulin
Once a significant number of islet cells are destroyed, you'll produce little or no insulin. Insulin is a hormone that comes from a gland situated behind and below the stomach (pancreas).
- The pancreas secretes insulin into the bloodstream.
- Insulin circulates, allowing 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 glucose as glycogen.
- When your glucose levels are low, such as when you haven't eaten in a while, the liver breaks down the stored glycogen into glucose to keep your glucose levels within a normal range.
In type 1 diabetes, there's no insulin to let glucose into the cells, so sugar builds up in your bloodstream. This can cause life-threatening complications.