Hyperglycemia (High Blood Glucose)

Hyperglycemia is the technical term for high blood glucose (blood sugar). High blood glucose happens when the body has too little insulin or when the body can't use insulin properly.

What Causes Hyperglycemia?

A number of things can cause hyperglycemia:

  • If you have type 1, you may not have given yourself enough insulin.
  • If you have type 2, your body may have enough insulin, but it is not as effective as it should be.
  • You ate more than planned or exercised less than planned.
  • You have stress from an illness, such as a cold or flu.
  • You have other stress, such as family conflicts or school or dating problems.
  • You may have experienced the dawn phenomenon (a surge of hormones that the body produces daily around 4:00 a.m. to 5:00 a.m.).

What are the Symptoms of Hyperglycemia?

The signs and symptoms include the following:

  • High blood glucose
  • High levels of sugar in the urine
  • Frequent urination
  • Increased thirst

Part of managing your diabetes is checking your blood glucose often. Ask your doctor how often you should check and what your blood glucose levels should be. Checking your blood and then treating high blood glucose early will help you avoid problems associated with hyperglycemia.

How Do I Treat Hyperglycemia?

You can often lower your blood glucose level by exercising. However, if your blood glucose is above 240 mg/dl, check your urine for ketones. If you have ketones, do not exercise.

Exercising when ketones are present may make your blood glucose level go even higher. You'll need to work with your doctor to find the safest way for you to lower your blood glucose level.

Cutting down on the amount of food you eat might also help. Work with your dietitian to make changes in your meal plan. If exercise and changes in your diet don't work, your doctor may change the amount of your medication or insulin or possibly the timing of when you take it.

What if it Goes Untreated?

Hyperglycemia can be a serious problem if you don't treat it, so it's important to treat as soon as you detect it. If you fail to treat hyperglycemia, a condition called ketoacidosis (diabetic coma) could occur. Ketoacidosis develops when your body doesn't have enough insulin. Without insulin, your body can't use glucose for fuel, so your body breaks down fats to use for energy.

When your body breaks down fats, waste products called ketones are produced. Your body cannot tolerate large amounts of ketones and will try to get rid of them through the urine. Unfortunately, the body cannot release all the ketones and they build up in your blood, which can lead to ketoacidosis.

Ketoacidosis is life-threatening and needs immediate treatment. Symptoms include:

  • Shortness of breath
  • Breath that smells fruity
  • Nausea and vomiting
  • Very dry mouth

Talk to your doctor about how to handle this condition.

Medical IDs

Many people with diabetes, particularly those who use insulin, should have a medical ID with them at all times.

In the event of a severe hypoglycemic episode, a car accident, or other emergency, the medical ID can provide critical information about the person's health status, such as the fact that they have diabetes, whether or not they use insulin, whether they have any allergies, etc. Emergency medical personnel are trained to look for a medical ID when they are caring for someone who can't speak for themselves.

Medical IDs are usually worn as a bracelet or a necklace. Traditional IDs are etched with basic, key health information about the person, and some IDs now include compact USB drives that can carry a person's full medical record for use in an emergency.

How Can I Prevent Hyperglycemia?

Your best bet is to practice good diabetes management and learn to detect hyperglycemia so you can treat it early — before it gets worse.

If you or your child has recently been diagnosed with type 1 diabetes, order our free Courage-Wisdom-Hope kit for children and their families. 

If you're new to type 2 diabetes, join our free Living With Type 2 Diabetes program to get help and support during your first year.

Personal Stories from The Type 1 Diabetes Self-Care Manual by Jamie Wood, MD and Anne Peters, MD

Type 1 Diabetes Self-Care Manual

On Day 9

On the day we began a cross-country move, our 15-month-old vomited all over the airport terminal. John threw up four more times over the next eight days. He was otherwise happy, despite waking up several times a night for bottles. We attributed that to the unfamiliar surroundings. After all, we did take him to the pediatrician after a few days and were told it was a virus. 

On Day 9 of this "virus," John was lethargic and refusing to eat or drink. One finger prick at the emergency room and all the pieces fell into place. Our boy has type 1 diabetes and was in DKA. The next 48 hours in the PICU were the scariest we have ever experienced. Four more days of training with a team of educators and we were sent home with an insulin pump on our toddler. 

While in the hospital, I feared that my happy, easy-going boy would never be the same, but John was playing with his sister within minutes of getting home. Six months later, we just returned from a family vacation full of airplanes, water parks and even ice cream. Planning ahead, site changes and BG checks are now routine. John is as happy as ever with a lifetime of possibilities ahead of him.

—Betsy Lennane

Her Face Went White

I developed type 1 diabetes in 1974 when I was 18 and in my first year of college. I began having all of the classic symptoms but didn’t know what that meant...Working too hard, eating badly, and perhaps a bit sick, I thought. After about three weeks, I returned home for spring break. While having breakfast I told my mother I had been feeling poorly and couldn’t see very well. She turned to me and said, “Come here.” Huh? Why? But I got up and walked to her. She stepped up to my face and said, “Breathe on me.” I was completely confused, but you don’t argue with Mother. I blew out a breath, and her face went white. She was smelling for acetone, a sign of untreated diabetes. Her father was diabetic and she knew that smell from her childhood. Within an hour I was admitted to the hospital.

—Sean McLin is a director of photography for motion pictures and television. He has had diabetes since 1973. 

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  • Last Reviewed: August 30, 2018
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