Hyperglycemia: High Blood Sugar Symptoms & Treatment | Cornerstones4Care®

High Blood Sugar

High blood sugar, also called hyperglycemia, happens when the body either has too little insulin, or can't use insulin properly.   A number of different things can cause people with type 1 diabetes to have high blood sugar, including:

  • Not taking enough insulin for the food eaten
  • Eating more than planned for the insulin taken
  • Being less active than planned
  • Physical stress from illnesses, such as a cold or the flu
  • Emotional stress or excitement  

According to the American Diabetes Association (ADA), blood sugar is considered high when it is 180 mg/dL or higher, or above a person’s recommended blood sugar target. Talk to your health care provider about what he or she thinks is a safe target for your blood sugar before and after meals.

Download and print this useful High Blood Sugar Fact Sheet.

This fact sheet is also available in Spanish.


Signs and symptoms of high blood sugar include

  • High blood sugar readings when testing
  • High levels of sugar in the urine
  • Frequent urination
  • Increased thirst

What to do about high blood sugar

One way to lower blood sugar is by physical activity. But, according to the American Diabetes Association (ADA), if the blood sugar number is higher than 240 mg/dL and not falling, do not exercise. Check your urine for ketones. Exercising with ketones can make blood sugar go even higher.  

What are ketones? Ketones are chemicals that the body creates when it breaks down fat for energy, rather than glucose. When too many ketones build up in the blood and urine it can lead to serious illness. This is called diabetic ketoacidosis (DKA).  When ketones are found in the urine, the health care provider needs to be called right away and there needs to be a discussion about how to safely lower blood sugar.

When blood sugar is too high, a dose of rapid-acting insulin is usually needed to bring it down, and fluids are necessary to prevent dehydration. If blood sugar is consistently too high, try cutting down on the amount of food you or the person you care for with diabetes is eating. Watch what is eaten to see how different foods affect blood sugar. Once an individual knows how their body reacts to foods, they can make changes in their meal plan so that their blood sugar will not rise too high, too quickly. 

Physical activity and changes to a meal plan will often bring down blood sugar. If this does not work, the person with diabetes may need to take more insulin. Talk to a health care provider before making any changes in the amount or timing of the insulin dose.  

Why is high blood sugar a problem?

High blood sugar can be serious if left untreated. In the long term, it may increase the risk for diabetes-related problems with the feet, eyes, kidneys, nerves, teeth, gums, heart, and blood vessels. In the short term, it could lead to a severe condition called DKA.  

What is DKA? It stands for diabetic ketoacidosis. It develops when the body doesn’t have enough insulin. Without insulin, sugar can’t get into the body’s cells to be used for fuel, so the body breaks down fats instead. But, when the body breaks down fats, it produces breakdown waste products called ketones. Ketones are very acidic and can change the pH of the blood to levels that are not safe. Ketoacidosis is very dangerous and needs immediate treatment.  

Signs of DKA include nausea and vomiting, stomach pain, fruity breath odor, and difficulty breathing. DKA is an emergency. Untreated DKA can lead to serious health risks. 

Signs and symptoms of DKA can include

  • High blood sugar above 240 mg/dL and not falling
  • Hyperglycemia symptoms, such as intense thirst, dry mouth, need to urinate frequently
  • Lack of appetite, or stomach pains
  • Vomiting or nausea
  • Blurry vision
  • Fever or warm, dry, or flushed skin
  • Trouble breathing
  • Weakness
  • Sleepiness
  • Fruity breath odor

DKA is a medical emergency. If you or your loved one have any of the above symptoms, contact your health care provider right away. 

How and when to test for ketones?

Ketones can be detected with a simple urine test using a test strip, similar to a blood-testing strip. Ask the doctor when and how to test for ketones. According to the ADA, urine should be checked for ketones when blood sugar is more than 240 mg/dL and not falling, or if the person with diabetes feels ill. When the person with diabetes is sick (for example, with a cold or the flu), check for ketones every 4 hours. Also, check for ketones when there are symptoms of DKA.  

What if the test shows high ketone levels?

If the diabetes care team has not told you what levels of ketones are too high for you, call if you find moderate amounts after more than one test. Often, your health care provider can tell you what to do over the phone. Call at once if the urine tests show high levels of ketones, especially if:

  • Blood sugar is very high (over 240 mg/dL) for 2 tests in a row or is not falling
  • The urine tests show moderate or large amounts of ketones and if you or the person you are caring for with diabetes has vomited 
  • High levels of ketones and high blood sugar can mean diabetes is out of control. Check with your health care provider about how to handle this right away—the sooner, the better!

Do You Go Too Low?

Severe low blood sugar, also known as hypoglycemia, can be very serious if not detected and treated immediately. Learn how to tell if you are running low and what to do about it.

Have You Joined Yet?

You’re on Cornerstones4Care.com, which is a great start! But did you know that there’s a lot more to the type 1 diabetes support program than just the website? From helpful emails to useful diabetes management tools, membership has its advantages.