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Nonketotic Hyperosmolar Syndrome

(Nonketotic Hyperosmolar Coma; Hyperosmolar Hyperglycemic State)

By Preeti Kishore, MD, Assistant Professor of Medicine, Division of Endocrinology, Albert Einstein College of Medicine

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Nonketotic hyperosmolar syndrome is a complication of diabetes mellitus that most often occurs in type 2 diabetes.

  • Symptoms of nonketotic hyperosmolar syndrome (NKHS) include extreme dehydration and confusion.

  • NKHS is diagnosed by blood tests that show very high levels of glucose and very concentrated blood.

  • Treatment is intravenous fluids and insulin.

  • Complications include coma, seizures, and death.

There are two types of diabetes mellitus, type 1 and type 2. In type 1 diabetes, the body produces almost no insulin, a hormone produced by the pancreas that helps sugar (glucose) move from the blood into the cells. In type 2 diabetes, the body produces insulin, but cells fail to respond normally to the insulin. In both types of diabetes. the amount of sugar (glucose) in the blood is elevated.

If people with type 1 diabetes receive no insulin, or they need more insulin because of an illness, fat cells begin breaking down to provide energy. Fat cells that break down produce substances called ketones. Ketones provide some energy to cells but also make the blood too acidic (ketoacidosis). Diabetic ketoacidosis is a dangerous, sometimes life-threatening, disorder.

Because people with type 2 diabetes produce some insulin, ketoacidosis does not usually develop even when type 2 diabetes is untreated for a long time. However, the blood glucose levels can become extremely high (often exceeding 1,000 mg per deciliter of blood). Such very high blood glucose levels cause the person to pass large amounts of urine, which eventually causes severe dehydration and makes the person's blood abnormally concentrated (hyperosmolar). Thus, the disorder is called nonketotic hyperosmolar syndrome.


Nonketotic hyperosmolar syndrome can occur for two main reasons

  • People stop taking the drugs for their diabetes

  • An infection or other illness stresses the body

Also, certain drugs, such as corticosteroids, can raise blood glucose levels and cause nonketotic hyperosmolar syndrome. Drugs such as diuretics, which people often take to treat high blood pressure, can worsen dehydration and trigger nonketotic hyperosmolar syndrome.


The main symptoms of nonketotic hyperosmolar syndrome are mental changes. The changes range from mild confusion and disorientation to drowsiness and coma. Some people have seizures and/or temporary partial paralysis resembling a stroke. Up to 40% of people die.


  • Blood tests to measure glucose level

Doctors suspect the diagnosis of nonketotic hyperosmolar syndrome when people who have recently developed confusion are found to have a very high blood glucose level. They confirm the diagnosis by doing additional blood tests that show very concentrated blood and lack of ketones or acidity in the bloodstream.


  • Fluids and electrolytes given by vein

Nonketotic hyperosmolar syndrome is treated much like diabetic ketoacidosis. Fluids and electrolytes must be replaced intravenously. The levels of glucose in the blood must be restored to normal levels gradually to avoid sudden shifts of fluid within the brain. The blood glucose levels tend to be more easily controlled than in diabetic ketoacidosis, and blood acidity problems are not severe.