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Symptoms of High Blood Sugar - Topic Overview

High blood sugar (hyperglycemia) is most often seen in people who have diabetes that isn't well controlled. The symptoms of high blood sugar can be mild, moderate, or severe.

Mild high blood sugar

If your blood sugar levels are consistently 200 milligrams per deciliter (mg/dL) to 350 mg/dL, you may have mild symptoms of high blood sugar. You may urinate more than usual if you are drinking plenty of liquids. Some people who have diabetes may not notice any symptoms when their blood sugar level is in this range. The main symptoms of high blood sugar are:

  • Increased thirst.
  • Increased urination.
  • Weight loss.
  • Fatigue.
  • Increased appetite.

Young children are unable to recognize symptoms of high blood sugar. Parents need to do a home blood sugar test on their child whenever they suspect high blood sugar. Children have mild high blood sugar when their blood sugar levels are between 200 mg/dL and 240 mg/dL.

If you don't drink enough liquids to replace the fluids lost from high blood sugar levels, you can become dehydrated. Young children can become dehydrated very quickly. Symptoms of dehydration include:

  • A dry mouth and increased thirst.
  • Warm, dry skin.

Moderate to severe high blood sugar

If your blood sugar levels are consistently high (usually above 350 mg/dL in adults and above 240 mg/dL in children), you may have moderate to severe symptoms of high blood sugar. These symptoms include:

  • Blurred vision.
  • Extreme thirst.
  • Lightheadedness.
  • Flushed, hot, dry skin.
  • Restlessness, drowsiness, or difficulty waking up.

If your body produces little or no insulin (people with type 1 diabetes and some people with type 2 diabetes), you also may have:

  • Rapid, deep breathing.
  • A fast heart rate and a weak pulse.
  • A strong, fruity breath odor.
  • Loss of appetite, belly pain, and/or vomiting.

If your blood sugar levels continue to rise, you may become confused and lethargic. You also may become unconscious if your blood sugar levels are very high.

WebMD Medical Reference from Healthwise

Last Updated: June 24, 2013
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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If the level is below 70 or you are experiencing symptoms such as shaking, sweating or difficulty thinking, you will need to raise the number immediately. A quick solution is to eat a few pieces of hard candy or 1 tablespoon of sugar or honey. Recheck your numbers again in 15 minutes to see if the number has gone up. If not, repeat the steps above or call your doctor.

People who experience hypoglycemia several times in a week should call their health care provider. It's important to monitor your levels each day so you can make sure your numbers are within the range. If you are pregnant always consult with your health care provider.

Congratulations on taking steps to manage your health.

However, it's important to continue to track your numbers so that you can make lifestyle changes if needed. If you are pregnant always consult with your physician.

Your level is high if this reading was taken before eating. Aim for 70-130 before meals and less than 180 two hours after meals.

Even if your number is high, it's not too late for you to take control of your health and lower your blood sugar.

One of the first steps is to monitor your levels each day. If you are pregnant always consult with your physician.

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