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High Blood Glucose: What It Means and How To Treat It

What is high blood glucose?

People who do not have diabetes typically have fasting plasma blood glucose levels that run under 100 mg/dl.

Your physician will define for you what your target blood glucose should be — identifying a blood glucose target that is as close to normal as possible that you can safely achieve given your overall medical health. In general, high blood glucose, also called 'hyperglycemia', is considered "high" when it is 160 mg/dl or above your individual blood glucose target. Be sure to ask your healthcare provider what he or she thinks is a safe target for you for blood glucose before and after meals.

If your blood glucose runs high for long periods of time, this can pose significant problems for you long-term — increased risk of complications, such as eye disease, kidney disease, heart attacks and strokes and more. High blood glucose can pose health problems in the short-term as well. Your treatment plan may need adjustment if the blood glucose stays over 180 mg/dl for 3 days in a row. It is important to aim to keep your blood glucose under control, and treat hyperglycemia when it occurs.

What are the symptoms of high blood glucose?

  • Increased thirst
  • Increased urination
  • Dry mouth or skin
  • Tiredness or fatigue
  • Blurred vision
  • More frequent infections
  • Slow healing cuts and sores
  • Unexplained weight loss

What causes high blood glucose?

  • Too much food
  • Too little exercise or physical activity
  • Skipped or not enough diabetes pills or insulin
  • Insulin that has spoiled after being exposed to extreme heat or freezing cold
  • Stress, illness, infection, injury or surgery
  • A blood glucose meter that is not reading accurately

What should you do for high blood glucose?

  • Be sure to drink plenty of water. It is recommended to drink a minimum of 8 glasses each day.
  • If your blood glucose is 250 or greater and you are on insulin, check your urine for ketones. If you have ketones, follow your sick day rules or call your healthcare team if you are not sure what to do.
  • Ask yourself what may have caused the high blood sugar, and take action to correct it. Ask your healthcare team if you are not sure what to do.
  • Try to determine if there is a pattern to your blood glucose levels.
    • Check your blood glucose before meals 3 days in a row.
    • If greater than your target level for 3 days, a change in medication may be needed.
    • Call your healthcare team or adjust your insulin dose following well day rules.
    • Call your healthcare team if you are currently using diabetes pills.

Determine why your blood glucose is high

Ask yourself the questions outlined below. The answers will give you the information you need to determine what to do about the hyperglycemia.



Ask These Questions

Take Action


If your answers to the questions are yes, follow these suggestions.


Have you increased your portion sizes?
Have you changed your eating habits or food choices?
Have you eaten too many high-fat foods?

You may need to measure food more accurately to check portion control. If you think your eating pattern is changing, your medication or exercise plan may need to change.


Have you decreased or eliminated your usual activity?
Are you doing too little physical activity?

Physical activity is a key to blood glucose control. Ask your healthcare team about starting a program.


Have you been taking the prescribed doses?
Have you been taking the medication at the right time?

Do you have "spoiled" insulin?

  • Does your insulin look different?
  • Was your insulin exposed to very hot or cold temperatures?
  • Has your insulin expired?

Take the right dose at the right time. If you have any questions ask a diabetes educator.


Throw away the bottle and open a new bottle.


Check the expiration date on bottle.


Is the drop of blood too small?
Are you using the correct technique?
Could your meter be dirty?
Have your strips expired?
Have your strips been exposed to very hot or cold temperatures or not been kept in an airtight, dry, container?
Is your meter calibrated to the current bottle of strips?

See a nurse educator to be sure your technique is correct and your meter is functioning the right way. Learn how to clean the meter.

Throw away the strips and get a new bottle. Check the code on the strip bottle.

Illness, infection, injury and surgery

Are you feeling well?
Do you have any infections?

Follow sick day rules.
Contact your healthcare team for questions or help.

Attention visitors from outside the US: You can easily convert US to non-US blood glucose levels by clicking here.

Page last updated: November 07, 2019