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Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS)

What is hyperosmolar hyperglycemic nonketotic syndrome?

Having diabetes means that there is too much sugar (glucose) in your blood. When you eat food, your body breaks down much of the food into glucose. Your blood carries the glucose to the cells of your body. An organ in your upper belly, called the pancreas, makes and releases a hormone called insulin when it detects glucose. Your body uses insulin to help move the glucose from the bloodstream into the cells for energy. When your body does not make insulin (type 1 diabetes), or has trouble using insulin (type 2 diabetes), glucose cannot get into your cells. The glucose level in your blood goes up. Too much glucose in your blood (also called hyperglycemia or high blood sugar) can cause many problems.

People with type 2 diabetes are at risk for a problem called hyperosmolar hyperglycemic nonketotic syndrome (HHNS). It is very rare in people with type 1 diabetes. HHNS is an emergency caused by very high blood sugar, often over 600 mg/dL. Your kidneys try to get rid of the extra blood sugar by putting more sugar into the urine. This makes you urinate more and you lose too much body fluid, causing dehydration. As you lose fluids, your blood becomes thicker and your blood sugar level gets too high for the kidneys to be able to fix. With the high blood sugar and dehydration, there is also an imbalance of minerals, especially sodium and potassium in the blood. The imbalance of fluids, glucose, and minerals in the body can lead to severe problems, such as brain swelling, abnormal heart rhythms, seizures, coma, or organ failure. Without rapid treatment, HHNS can cause death.

What can I expect in the hospital?

You will need to stay in the hospital in order to bring your blood sugar level under control and treat the cause of the HHNS. Several things may be done while you are in the hospital to monitor, test, and treat your condition. They include:


  • You will be checked often by the hospital staff.
  • You may have fingersticks to check your blood sugar regularly. This may be done as often as every hour. You will learn how to check your blood sugar level in order to manage your diabetes when you go home.
  • A heart (cardiac) monitor may be used to keep track of your heartbeat.
  • Your blood oxygen level may be monitored by a sensor that is attached to your finger or earlobe.
  • Your fluid intake may be monitored closely by keeping track of everything you eat and drink and any IV fluids you receive.
  • You may have a small tube (catheter) placed into your bladder through the urethra (the opening from the bladder to the outside of the body) to drain and measure urine from the bladder.


Testing may include:

  • Blood tests (Hemoglobin A1c) to check your average blood sugar over the past 3 months
  • Blood or urine tests to check for infections
  • Blood tests to test for mineral (sodium and potassium) levels
  • Blood tests to check blood thickness and its ability to form clots
  • Blood tests to check to see if your body is making insulin
  • Blood, urine, or other tests to monitor how well your organs are functioning
  • Arterial blood gas (ABG): A blood test to measure the levels of oxygen and carbon dioxide in your blood
  • X-rays: Pictures of the inside of the chest to check for infection


The treatment for HHNS depends on the cause and how well you respond to treatment. The goal of treatment is to return your blood sugar to a normal level and keep it in a normal range. Treatment may include:

  • You will have a small tube (IV catheter) inserted into a vein in your hand or arm. This will allow medicine to be given directly into your blood and to give you fluids, if needed.
  • Your provider may prescribe medicines to:
    • Keep your blood sugar controlled
    • Treat other medical problems that may have been caused by or made worse because of diabetes
    • Treat pain
    • Treat or prevent an infection
    • Prevent blood clots
    • Prevent side effects, such as nausea or constipation, from other treatments
    • Replace vitamins and minerals
  • You may receive oxygen through a small tube placed under your nose or through a mask placed over your face.
  • If you develop blood clots, you may need surgery to remove them.
  • You may need kidney dialysis to help filter your blood if your kidneys are not working properly.

What can I do to help?

  • You will need to tell your healthcare team if you have new or worsening:
    • Fainting
    • Weakness, numbness, tingling or pain in your face, arm, or leg, especially on one side of your body
    • Seizures
    • Increased urination or trouble emptying the bladder
    • Increased thirst and dry mouth
    • Tiredness
    • Confusion
    • Hallucinations, which may be visual or involve other senses, such as hearing, touching, tasting or seeing something that is not really there
    • Fast or irregular heartbeat
    • Change in vision, such as double vision, blurred vision, or trouble seeing out of one or both eyes
    • Signs of infection around your surgical wound if you had surgery. These include:
      • The area around your wound is more red or painful
      • The wound area is very warm to touch
      • You have blood, pus, or other fluid coming from your wound area
      • You have chills or muscle aches
  • Ask questions about any medicine or treatment or information that you do not understand.

How long will I be in the hospital?

How long you stay in the hospital with HHNS depends on your general health and how bad the complications are. A healthy person with no medical problems other than diabetes and no HHNS complications may stay in the hospital 3 to 5 days. You may be in an intensive care unit at the hospital for at least the first day or two. A person with other medical problems or HHNS complications may need to stay in the hospital much longer.

Developed by RelayHealth.
Acute Care Advisor 2015.1 published by RelayHealth.
Last modified: 2014-04-30
Last reviewed: 2014-04-24
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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