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Type 2 Diabetes - Cause

Causes of diabetes

Type 2 diabetes occurs when your blood sugar (glucose) levels get too high because:

  • Your body isn't able to use insulin the right way. This makes it hard for your cells to get glucose from blood to make energy. This is called insulin resistance.
  • Your pancreas doesn't make enough insulin to make up for the insulin resistance. As type 2 diabetes gets worse, your pancreas may make less and less insulin. This is called insulin deficiency.

Your weight, how much physical activity you get, and your family history may affect the way your body responds to insulin.

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Causes of high blood sugar

High blood sugar can happen if you:

  • Skip a dose of your type 2 diabetes medicine or skip a required dose of insulin.
  • Eat too much.
  • Exercise less than what you are used to doing.
  • Are taking medicines that raise blood sugar as a side effect, such as sleeping pills, some anti-inflammatory medicines (corticosteroids), and some decongestants.
  • Are stressed or ill, especially if you aren't eating or drinking enough. Plan ahead with your doctor and write down sick-day guidelines, which may include testing for ketones.

Being pregnant can also make your blood sugar levels go up.

If you take insulin, you may have some mornings when your blood sugar level is very high, even if it was low when you went to bed. This could be caused by the dawn phenomenon or the Somogyi effect. Talk with your doctor if this happens. You may need to check your blood sugar during the night to find out why your levels are high in the morning.

Causes of low blood sugar

You aren't likely to get low blood sugar unless you take insulin or some kinds of oral medicines that can cause low blood sugar. You may get low blood sugar if you:

  • Take too much diabetes medicine in a day, take your doses too close together, or take your full dose of medicine when you aren't going to eat your usual amount of food.
  • Exercise too much without eating enough food.
  • Skip a meal.
  • Drink too much alcohol, especially on an empty stomach.
  • Take medicines for other conditions that can lower blood sugar, such as large doses of aspirin and medicines for mental health problems.
  • Have problems with your kidneys.
  • Start to have other problems with your glands and hormones, such as Addison's disease or hypothyroidism.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Medical Reference from Healthwise

    Last Updated: January 24, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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