For Kids: High Blood Sugar

Boy drinking a glass of water.

Your body needs energy to do things. Energy comes from a kind of sugar found in the food you eat. This sugar is called glucose. Glucose travels in your blood. Without glucose you wouldn’t be able to study, play, or even eat or think. But if too much glucose builds up in your blood, you can feel sick. This is called high blood sugar (hyperglycemia). High blood sugar happens when you eat too much or don’t take enough insulin. It can also happen when you’re sick, worried, upset, or excited. If your blood sugar gets really high, it can be dangerous.

What do “highs” feel like?

You probably felt some of the symptoms of high blood sugar (“highs”) right before you found out you had diabetes. These are some symptoms of high blood sugar:

  • Being very thirsty

  • Needing to pee a lot

  • Weakness

  • Dizziness

  • Tiredness

  • Muscle cramps

  • Headache

  • Blurry eyesight

  • Feeling sick to your stomach

  • Hungry all the time

  • Losing weight

  • High levels of sugar in the urine

High blood sugar can be dangerous. And people with diabetes sometimes don’t feel any symptoms when they have high blood sugar. So, to be safe, test your blood sugar as often as you’ve been told to.

You can prevent highs

Don’t let highs get you down. Follow these two rules:

Rule #1: Always take your insulin. Follow the plan you work out with your healthcare team and make sure you review it periodically. 

Rule #2: Stick to your diet plan. Eat the right amount of food at your meals and snacks. 

You can treat highs

No matter how good you get at avoiding highs, they will happen from time to time. If you feel like you might be having a high, check your blood sugar right away. Or, have an adult check it for you. Then, do the following:

  • If your blood sugar is over 250, tell your parents or another adult right away. You will need to check for ketones in your urine. (Your healthcare team will show you how.)

  • Drink water or other sugar-free drinks. They help wash away ketones. (Ketones leave the body when you pee.)

  • You may need to take extra insulin. Your healthcare team will teach you how to figure out how much extra insulin to take when you’re having a high.

Playing it smart

Playing sports and being active can cause your blood sugar level to go up or down. Avoid highs by playing it smart:

  • Always test your blood sugar before you exercise.

  • If your blood sugar is 250 mg/dL or above, test for ketones. If ketone levels are high, tell your parents or another adult right away. If ketone levels are low, you may do mid- to moderate-intensity exercise.

  • Don't do intense exercise until your blood sugar is below 250 mg/dL. Intense exercise may make your blood sugar higher.

  • Drink lots of water, especially when you’re exercising.

  • Tell an adult right away if you feel like you’re having a high.


Still have questions about diabetes? Check out these websites:

  • American Diabetes Association,

  • Children with Diabetes,

  • Juvenile Diabetes Research Foundation,