Hyperglycemia and Type 2 Diabetes

Written by Kimberly Holland | Published on January 20, 2012
Medically Reviewed by Peggy Pletcher, MS, RD, LD, CDE on April 29, 2014


High blood glucose, also known as hyperglycemia, can cause major health complications in people with diabetes. Several factors can contribute to hyperglycemia—including poor food and physical activity choices, illness or disease, or not getting the right dosage of glucose-lowering medication.

Regular blood sugar testing is helpful for people with diabetes, because many people do not feel symptoms of high blood sugar. Short-term symptoms of high blood sugar include:

  • excessive thirst
  • excessive urination
  • increased urination at night
  • blurry vision
  • sores that won’t heal
  • fatigue

If you experience symptoms of hyperglycemia, it’s important that you check your blood glucose levels. Untreated high blood sugar can lead to acute complications, such as diabetic ketoacidosis, and chronic complications, such as eye, kidney, or heart disease and/or nerve damage.

What Are the Symptoms of Hyperglycemia?

Hyperglycemia rarely causes noticeable symptoms. Symptoms can develop over several days or weeks, and the longer the condition is left untreated, the more severe the problem may become. The signs and symptoms of hyperglycemia include:

  • blood glucose level greater than 180 mg/dL
  • blurry vision
  • difficulty concentrating
  • frequent urination
  • headaches
  • high blood glucose
  • high levels of sugar in the urine
  • increased fatigue
  • increased thirst
  • weight loss

What Causes Hyperglycemia?

A number of conditions or factors can contribute to hyperglycemia, including:

  • being less active than normal
  • eating more carbohydrates than usual without adequate insulin
  • having more stress than usual—from an illness or from outside sources such as family conflict, relationship problems, or financial concerns (illness and stress can trigger hormones that can cause your blood sugar to rise)
  • taking less diabetes medication than normal
  • not injecting insulin properly or using expired insulin
  • skipping or forgetting insulin or medicine

How Is Hyperglycemia Treated?

Monitoring Glucose Levels

An important part of managing your diabetes is checking your blood glucose level often—and then recording that number in a notebook or blood glucose log so you and your doctor can monitor your treatment plan. Knowing when your blood glucose levels are getting out of your target range can help you get blood sugar back under control before more significant problems arise.

Get Moving

Exercise is one of the best and most effective ways to keep your blood glucose levels where they should be, and lower them if they get high.  If you are on medications that increase insulin, be sure to talk to your healthcare team to decide the best times to exercise.  If you have complications such as nerve or eye damage, talk to your healthcare team about exercises that are best for your situation.

An important note: If your blood glucose is above 240 mg/dl, it’s vital that you check your urine for ketones. If you have ketones, do not exercise. Do not exercise if your blood glucose is above 300 mg/dL even without ketones. Call your doctor instead. Exercising when ketones are in your body may cause your blood glucose level to go even higher.

Analyze Your Eating Habits

Meet with a dietitian or nutritionist and work together to construct a healthy, interesting selection of meals that can help prevent higher blood glucose levels.

Evaluate Your Treatment Plan

Depending on your personal health history and your experiences with hyperglycemia, your doctor may wish to change the amount, type, or timing of your diabetes medication. Do not adjust your medicines without first talking to your doctor or nurse educator.

In rare cases, emergency treatment is needed to lower your blood sugar. This type of treatment usually includes replacing fluids lost during excessive urination; electrolyte replacement, to replace minerals in your body lost as a result of inadequate insulin; and insulin therapy, to reverse the buildup of ketones in your blood.

If you have a history of hyperglycemia, talk with your doctor about safe, practical ways to control your blood glucose. Cutting back on the amount of certain foods you eat might help, as can changing your medication or insulin.

What Are the Complications of Hyperglycemia?

Untreated and chronic hyperglycemia can cause serious complications. These include:

  • nerve damage (neuropathy)
  • kidney damage (nephropathy) or kidney failure
  • cardiovascular disease
  • eye disease (retinopathy)
  • foot problems caused by damaged nerves and poor blood flow
  • skin problems, such as bacterial and fungal infections 

Emergency Complications

If your blood sugar goes high enough or is too high for a prolonged period of time, you may begin developing symptoms of two serious conditions. They are:


This is a buildup of ketones in your blood and urine. It can be poisonous and might lead to a life-threatening diabetic coma.

Diabetic Hyperosmolar Syndrome

If insulin is present but not working properly, blood glucose levels may get as high as 600 mg/dL. The body cannot use glucose or fat for energy, so the glucose is dumped into the urine, which causes more-frequent urination. If left untreated, hyperosmolar syndrome may lead to life-threatening dehydration and even coma.

How Is Hyperglycemia Prevented?

Good diabetes management and careful monitoring of your blood glucose are both very effective means for preventing hyperglycemia—or stopping it before it gets worse.

Test Regularly

Test and record your blood glucose levels on a regular basis each day. Share this information with your doctor at every appointment.

Count Carbs

Know how many carbohydrates you’re eating in a day, and strive to stay in the range approved by your doctor or nurse educator. Keep this information with your blood sugar levels.

Be Diabetes Smart

Have a plan of action for if and when your blood glucose reaches certain levels. Take your medication as prescribed, being consistent about the amount and timing of your meals and snacks.

Wear Medical Identification

Medical bracelets or necklaces can help alert emergency responders to your diabetes if there is a greater problem.


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Show Sources

  • Diabetic hyperglycemic hyperosmolar syndrome: MedlinePlus Medical Encyclopedia. (n.d.). National Library of Medicine - National Institutes of Health. Retrieved January 20, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/000304.htm
  • Hyperglycemia (High blood glucose) - American Diabetes Association. (n.d.). American Diabetes Association. Retrieved January 20, 2012, from http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hyperglycemia.html
  • Hyperglycemia in diabetes - MayoClinic.com. (n.d.). Mayo Clinic. Retrieved January 20, 2012, from http://www.mayoclinic.com/health/hyperglycemia/DS01168

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