CausesBy Mayo Clinic staff
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.
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