Type 1 diabetes develops because the body's immune system destroys beta cells in a part of the pancreas called the islet tissue. These beta cells produce insulin. So people with type 1 diabetes can't make their own insulin.
The pancreas normally adjusts the amount of insulin it makes based on your changing blood sugar. When you have diabetes, your insulin injections can't control your blood sugar moment to moment, the way your pancreas would. So you may have high and low blood sugar levels from time to time.
Causes of high blood sugar
Causes of high blood sugar include:
- Not getting enough insulin.
- Eating more food than usual.
- Stress and being ill (such as with severe flu) or having an infection, especially if you aren't eating or drinking enough.
- Taking medicines that can raise blood sugar levels, such as those for sleep, some decongestants, and corticosteroids (such as prednisone).
- The dawn phenomenon or the Somogyi effect, which can cause early-morning high blood sugar.
- Adolescence, because of hormone changes and rapid growth.
Sometimes a person's blood sugar level rises greatly before he or she knows something is wrong. Because insulin isn't available, the cells in the body are unable to get the sugar (glucose) they need for energy. The body begins to break down fat and muscle for energy.
Causes of low blood sugar
Causes of low blood sugar include:
- Taking too much insulin.
- Skipping or delaying a meal or snack.
- Exercising more than usual without eating enough food.
- Drinking too much alcohol, especially on an empty stomach.
- Taking medicines that can lower blood sugar, such as large amounts of aspirin and medicines for mental disorders.
- Starting your menstrual period, because hormonal changes may affect how well insulin works.