Diabetic hyperglycemic hyperosmolar coma

Alternative names
Nonketotic hyperglycemic coma; NKHHC; HONK - hyperosmolar non-ketotic coma

Diabetic hyperglycemic hyperosmolar coma is a complication of type 2 diabetes that results in extremely high glucose levels without the presence of ketones (a by-product of fat that can cause other Complications).

Causes, incidence, and risk factors

Diabetic hyperglycemic hyperosmolar coma is a condition of decreased consciousness, extreme dehydration (lack of water), and extremely high blood glucose (sugar) levels, which is not accompanied by ketoacidosis.

The condition is usually seen in people with non-insulin-dependent diabetes (type 2 diabetes) and may occur in those previously undiagnosed with diabetes or in those who have improperly managed their medications and diet. The condition may be brought on by an infection or by certain medications that impair glucose tolerance or increase fluid loss.

Normally, the kidneys compensate for high glucose levels in the blood by excreting excess glucose in the urine. However, when water is scarce, the kidneys conserve fluid, and glucose levels become higher. This results in greater need for water.

Hyperosmolarity is a condition in which the blood is concentrated with sodium, glucose, and other molecules that normally attract water into the bloodstream. When the kidneys are conserving water, however, this creates a vicious cycle of increasing blood-glucose levels and increasing dehydration.

Risk factors include:

  • Older age  
  • Underlying kidney insufficiency  
  • Congestive heart failure  
  • Recent discontinuation of insulin or oral hypoglycemic agents  
  • Improper management of diabetes  
  • A precipitating event such as infection, heart attack, stroke, or recent surgery.


  • Weakness  
  • Increased thirst  
  • Nausea  
  • Lethargy  
  • Confusion  
  • Convulsions  
  • Coma

The onset of symptoms may be over a period of days or weeks.

Additional symptoms that may be associated with this disease:

  • Speech impairment  
  • Loss of feeling or function of muscles  
  • Dysfunctional movement

Signs and tests

Vital signs (temperature, pulse, rate of breathing, blood pressure):

  • Temperature - higher than 38 degrees Centigrade (100.4 degrees Fahrenheit)  
  • Heart rate - greater than 100  
  • Systolic blood pressure - low (less than 100)


  • Blood glucose - severely elevated (from 600 to 2,400 mg/dL)  
  • Elevated serum osmolarity  
  • Elevated serum sodium  
  • Evaluation for possible underlying causes       o Chest x-ray       o Blood cultures       o Urinanalysis       o Electrocardiogram (ECG)

The goal of treatment is to correct the dehydration, which will improve the blood pressure, urine output, and poor circulation. Fluids and potassium are replaced by intravenous therapy. High glucose levels are treated with intravenous insulin.

Expectations (prognosis)
The death rate associated with this condition is as much as 40%.


  • Acute circulatory collapse (shock)  
  • Blood clot formation  
  • Brain swelling (cerebral edema)  
  • Increased blood acid levels (lactic acidosis)

Calling your health care provider
This condition is a MEDICAL EMERGENCY! Go to the emergency room or call the local emergency number (such as 911) if signs or symptoms of diabetic hyperglycemic hyperosmolar coma develop.

Good control of type 2 diabetes, coupled with recognition of early signs of dehydration and infection, can help prevent this condition.

Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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