Health Information

Diabetic hyperglycemic hyperosmolar syndrome

Diabetic hyperglycemic hyperosmolar syndrome


Hyperglycemic hyperosmolar coma; Nonketotic hyperglycemic hyperosmolar coma (NKHHC); Hyperosmolar nonketotic coma (HONK)

Diabetic hyperglycemic hyperosmolar syndrome (HHS) is a complication of type 2 diabetes that involves extremely high blood sugar (glucose) levels without the presence of ketones. Ketones are byproducts of fat breakdown.

I Would Like to Learn About:

  • Causes

    Diabetic hyperglycemic hyperosmolar syndrome is a condition of:

    • Extremely high blood sugar (glucose) levels
    • Extreme lack of water (dehydration)
    • Decreased consciousness

    The buildup of ketones in the body (ketoacidosis) may also occur. However, it is unusual and often mild.

    This condition is usually seen in people with type 2 diabetes. It may occur in those who have not been diagnosed with diabetes, or in people who have not been able to control their diabetes. The condition may be brought on by:

    • Infection
    • Other illness such as heart attack or stroke
    • Medications that lower glucose tolerance or increase fluid loss (in people who are losing or not getting enough fluid)

    Normally, the kidneys try to make up for high glucose levels in the blood by allowing the extra glucose to leave the body in the urine. If you do not drink enough fluids, or you drink fluids that contain sugar, the kidneys can no longer get rid of the extra glucose. Glucose levels in the blood can become very high as a result. The blood then becomes much more concentrated than normal (hyperosmolarity).

    Hyperosmolarity is a condition in which the blood has a high concentration of salt (sodium), glucose, and other substances that normally cause water to move into the bloodstream. This draws the water out of the body's other organs, including the brain. Hyperosmolarity creates a cycle of increasing blood glucose levels and dehydration.

    Risk factors include:

    • A stressful event such as infection, heart attack, stroke, or recent surgery
    • Congestive heart failure
    • Impaired thirst
    • Limited access to water (especially in patients with dementia or who are bedbound)
    • Older age
    • Poor kidney function
    • Poor management of diabetes -- not following the treatment plan as directed
    • Stopping insulin or other medications that lower glucose levels
  • Symptoms

    • Coma
    • Confusion
    • Convulsions
    • Fever
    • Increased thirst
    • Increased urination (at the beginning of the syndrome)
    • Lethargy
    • Nausea
    • Weakness
    • Weight loss

    Symptoms may get worse over a period of days or weeks.

    Other symptoms that may occur with this disease:

    • Dysfunctional movement
    • Loss of feeling or function of muscles
    • Speech impairment
  • Exams and Tests

    The doctor or nurse will examine you and ask questions about your symptoms and medical history. The exam may show that you have: 

    • Extreme dehydration
    • Fever higher than 100.4 degrees Fahrenheit
    • Increased heart rate
    • Low systolic blood pressure

    Test that may be done include:

    • Blood osmolarity (concentration)
    • BUN and creatinine levels
    • Blood sodium level
    • Ketone test
    • Very high blood glucose

    Evaluation for possible causes may include:

    • Blood cultures
    • Chest x-ray
    • Electrocardiogram (ECG)
    • Urinalysis
  • Treatment

    The goal of treatment is to correct the dehydration. This will improve the blood pressure, urine output, and circulation.

    Fluids and potassium will be given through a vein (intravenously). High glucose levels are treated with insulin given through a vein.

  • Outlook (Prognosis)

    Patients who develop this syndrome are often already ill. The death rate with this condition is as high as 40%.

  • Possible Complications

    • Acute circulatory collapse (shock)
    • Blood clot formation
    • Brain swelling (cerebral edema)
    • Increased blood acid levels (lactic acidosis)
  • When to Contact a Medical Professional

    This condition is a medical emergency. Go to the emergency room or call the local emergency number (such as 911) if you develop symptoms of diabetic hyperglycemic hyperosmolar syndrome.

  • Prevention

    Controlling type 2 diabetes and recognizing the early signs of dehydration and infection can help prevent this condition.

Related Information

  Alertness - decrea...DehydrationGlucose test - blo...Diabetic Ketoacido...Type 2 DiabetesHeart Failure Over...Heart attackStrokeAcuteLactic acidosis   Diabetes - what to...   Diabetes - type 2...Heart failureHeart attack and a...


Buse JB, Polonsky KS, Burant CF. Type 2 diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, Larsen PR, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier;2011:chap 31.

Inzucchi SE, Sherwin RS. Type 2 diabetes. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 237.


Review Date: 6/12/2012  

Reviewed By: Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; David Zieve, MD, MHA, Medical Director, A.D.A.M., Health Solutions, Ebix, Inc.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.


A.D.A.M. content is best viewed in IE9 or above, Fire Fox and Google Chrome browser.