Hyperosmolar Hyperglycemic State

(HHS; Hyperosmolar Nonketotic Coma; HHNC)


Hyperosmolar nonketotic state (HHS) or coma happens in people with diabetes. It is a severe event that needs care.


HHS is caused by very high glucose in the blood. It is often set off by an illness or infection. It can also happen if the diabetes treatment plan is not followed. The body passes extra glucose out in the urine. Too much urine will lower the levels of other important things in the body such as water. This can make it hard for the brain and heart to work.

Risk Factors

HHS can happen at any age. It is more common in older adults and people with type 2 diabetes. Other things that may increase the chance of HHS are:


HHS can take days or weeks to start. Warning signs of high blood glucose that leads to HHS are:

  • Dry mouth
  • Peeing often
  • Thirst
  • Warm, dry skin without sweating
  • Nausea or vomiting
  • Mental confusion
  • Seizures
  • High fever
  • Sleepiness
  • Vision loss
  • Hallucinations
  • Weakness


Tests for HHS may include:

  • Blood tests—to check levels of glucose and other things in your blood
  • Urine tests for glucose and ketones
  • Tests look for signs of infection

The heart may also be checked. An EKG can check your heart's electrical activity.


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Hospital care will be needed. The goal is to replace fluids and minerals that are low. Glucose will also be brought to normal levels. Treatment may include:

  • Fluids and minerals through an IV
  • Insulin through an IV—to help the body better use glucose in blood

Other treatment may be needed if there is an infection.


To help prevent HHS:

  • Check blood glucose levels as told.
  • Drink plenty of fluids throughout the day.
  • Make a care plan with your medical team. It should include how to handle diabetes when you are sick.


American Diabetes Association
National Institute of Diabetes and Digestive and Kidney Diseases


Canadian Diabetes Association


Hyperglycemic hyperosmolar state in adults. EBSCO DynaMed website. Available at: https://www.dyname... . Updated October 7, 2019. Accessed December 2, 2019.
Hyperglycemic hyperosmolar state in children. EBSCO DynaMed website. Available at: https://www.dyname... . Updated February 9, 2018. Accessed December 2, 2019.
Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. Hyperglycemic crises in adult patients with diabetes. Diabetes Care. 2009 Jul;32(7):1335-43EBSCOhost Full Text full-text, commentary can be found in Diabetes Care 2009 Dec;32(12):e157.
Scott A, Claydon A. Joint British Diabetes Societies Inpatient Care Group. The management of hyperosmolar hyperglycaemic state (HHS) in adults with diabetes. Joint British Diabetes Societies (JBDS) 2012 Aug PDF, summary of report can be found in Diabet Med 2015 Jun;32(6):714
Umpierrez G, Korytkowski M. Diabetic emergencies - ketoacidosis, hyperglycaemic hyperosmolar state and hypoglycaemia. Nat Rev Endocrinol. 2016 Apr;12(4):222-32
Last reviewed December 2019 by EBSCO Medical Review Board