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

Young children are not able 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.

Mild high blood sugar

You may have mild symptoms if your blood sugar levels are consistently higher than your target range. Some people may not notice any symptoms when their blood sugar level is in this range.

The main symptoms of mild high blood sugar are:

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

Moderate to severe high blood sugar

You may have moderate to severe symptoms if your blood sugar levels are consistently high. These symptoms include:

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

People with type 1 diabetes and some people with type 2 diabetes produce little or no insulin. These people may also 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 sluggish.
• Pass out (lose consciousness) if your blood sugar levels are very high.