Hyperglycemia and How to Treat It


Editor’s Note: This content has been verified by Anne Peters, MD, a professor of clinical medicine at the Keck School of Medicine of the University of Southern California and the director of the USC Clinical Diabetes Programs. Dr. Peters is an active member on the Beyond Type 1 Science Advisory Committee. 

What is hyperglycemia?

Hyperglycemia, or high blood sugar, occurs when glucose is trapped in the bloodstream due to a lack of insulin.  Glucose is a fuel source for the body and insulin brings it into your cells so they can use it for energy.  Without insulin the glucose stays in the blood stream instead of fueling your cells and can build up to high levels.

Most people without diabetes never have a blood glucose level above 7.8 mmol/L140 mg/dl, even after eating a lot of carbohydrates.  The normal fasting blood glucose level is 3.9 – 5.5 mmol/L70 – 100 mg/dl.  Diabetes is diagnosed if the morning (fasting) blood sugar is above 7.0 mmol/L126 mg/dl and/or the A1C is above 6.5%.  It is above these levels that complications of diabetes can occur.

Individual blood glucose ranges vary, so talk with your diabetes team about your threshold for high blood glucose levels.  Blood glucose levels can be high with or without symptoms; similarly blood glucose levels can sometimes be too low without symptoms.  It is why testing blood glucose levels is so important, either with fingersticks or a continuous glucose monitor.

If blood glucose levels are chronically high it can cause damage to the eyes, kidneys, nervous system and heart.  Sometimes acute hyperglycemia can lead to severe dehydration, diabetic ketoacidosis and coma.

Why does it occur?

There are three basic ways that blood sugar levels go up in the body.  First of all, every time you eat carbohydrates and protein your blood glucose levels increase.  Secondly, the liver is constantly making sugar.  Finally, illness, medications, hormones and stress can cause insulin resistance which brings blood glucose levels go up by making insulin act less well.  In someone without diabetes the body makes insulin for the food and makes the right amount of insulin to prevent the liver from making too much glucose.  If someone without diabetes is stressed and resistant to insulin, the pancreas just makes more insulin to deal with it.

When you have type 1 diabetes you have to give the right amount of insulin to deal with the food you eat, the glucose your liver makes and all the other situations of stress and illness (and menstrual cycles for women).  Sometimes you give too much and sometimes too little, which can result in low and high blood glucose levels.  It is always a balancing act, but there are new technologies that can help you manage it more easily.

Make a plan with your endocrinologist for sick days as your insulin needs may change (your pump may even have a “sick day” category in the basal settings). Keep a close eye on your blood sugar and check for ketones when you’re under the weather to prevent yourself from feeling the negative effects of hyperglycemia, too. Communicate with your diabetes team about how you’re feeling and ask questions about adjusting your insulin schedule.

Sometimes hyperglycemia can occur when insulin has expired or if it “goes bad,” from being exposed to extreme heat or cold. Store your insulin within appropriate temperature ranges to maintain its effectiveness.  Be sure to discard expired insulin.  Also, write down the date you open a vial or a pen—opened insulin has a much shorter shelf life than unopened insulin, usually 30 – 56 days.  You need to throw out your insulin if it is open past the date provided even if you still have some left.

Dr. Osama Hamdy of the Joslin Diabetes Center mentioned in Hypoglycemia and How to Treat It that overcorrecting a low can cause blood glucose levels to rebound or spike—also known as “rebounding.” If your blood sugar seems out of whack for no reason, it’s a good idea to check to see if your pump site or tubing is occluded, resulting in your body not properly absorbing insulin.

Possible signs and symptoms of Hyperglycemia

  • Unquenchable thirst
  • Dry mouth
  • Fatigue
  • Frequent urination
  • Blurred vision
  • Recurring infections
  • Slow-healing cuts or sores

Symptoms of Diabetes Ketoacidosis (DKA)

  • Fruity-smelling breath
  • Weight loss
  • Abdominal pain
  • Confusion
  • Presence of ketones
  • Vomiting
  • Exhaustion
  • Coma

How should I diagnose it?

  • Check your blood glucose level if you are feeling sick and then measure ketones (blood or urine) as advised by your diabetes team.
  • Check for ketones if your are sick and your blood glucose is above 16.6 mmol/L300 mg/dL (or whatever you are advised by your physician).
  • You may also need to check for ketones if your blood sugar level is unexpectedly high and doesn’t come down with a correction dose of insulin, particularly if you are on an insulin pump.
  • Report results to your diabetes team if your ketones are positive or above normal levels.

How should I treat?

  • If sick, follow sick day rules.
  • If your blood glucose levels are high without an explanation and you are sick or have ketones then avoid exercise. However, if your sugars are high because of eating carbohydrates and/or you do not have ketones then exercise can help lower your sugars.
  • Drink lots of water or electrolyte solution to help your body avoid dehydration and get rid of sugar in your urine.
  • Take a close look at your pump, tubing and infusion set to be sure there are no kinks or other problems that affect insulin delivery.
  • Make sure your insulin isn’t expired, or exposed to heat or cold or otherwise gone bad. You may need to try a fresh, unopened vial of insulin.
  • If you are vomiting and can’t keep fluid down you may need to go to the emergency department. If in doubt seek emergency care.  However, speaking to your diabetes team before the situation becomes too serious can often prevent the need for going to the hospital.

Along with a “sick day” plan, make a plan with your doctor about when you should seek medical assistance. Ask questions about the best way to treat hyperglycemia for you, what to do if you’re unable to keep food or liquids down, and the best way for preventing instances of hyperglycemia for you.

WRITTEN BY BT1 Editorial Team, POSTED 11/04/16, UPDATED 12/26/22

This piece was authored collaboratively by the Beyond Type 1 Editorial Team.