Hyperosmolar Hyperglycemic Non-Ketoacidosis (HHNK)

Hyperosmolar hyperglycemic non-ketoacidosis (HHNK) or simply non-ketoacidotic coma, is a serious acute complication of diabetes. It is considered a life-threatening emergency, and has known mortality rates as high as 5-20%. HHNK is commonly seen in persons with type 2 diabetes who are experiencing an illness (fever or urinary tract infection are common) that somehow leads to a decreased fluid intake. This can be either a decreased perception of thirst as sometimes seen in an older population, or a reduced ability to drink fluids, such as nausea and vomiting. As noted in a website article on HHNK, “… the elderly, the chronically ill, and institutionalized populations are at increased risk for HHNK. Any living situation or comorbidity that prevent adequate hydration, including for example immobility, advanced age, debility, dementia, agitation, impaired thirst response, restricted access to water, and restraint use, place these patients at risk.”- https://emedicine.medscape.com/article/1914705-overview#a5

HHNK is characterized by dehydration, and glucose levels as high as 600mg/dl or higher. Patients often experience some alteration in their level of consciousness (up to and including a comatose state). Unlike a person with type 1 diabetes, who may develop diabetic ketoacidosis when ill, most patients with HHNK do not develop significant ketoacidosis. Insulin remains available in small amounts, but insufficient to prevent hyperglycemia. Due to the high levels of glucose in the bloodstream, diuresis and dehydration occurs. HHNK patients have been known to lose large amounts of water volume. There have been reports of patients with HHNK having up to 9L of water deficit because of this diuresis. In addition, patients with HHNK have been observed with other symptoms such as high fevers, extremely dry mouth, increased thirst, weakness, confusion, dizziness and hallucinations.

As noted, this is a true medical emergency situation and persons with suspected HHNK need to be brought to the nearest Emergency Department. Initial care involves rehydration with intravenous fluids, electrolyte replacement therapy, treatment of any underlying infections, proper airway management, and extensive patient /provider education to reduce the risk of reoccurrence. Education would include strict monitoring of blood glucose levels and sick day management. Left untreated, HHNK can quickly progress to severe dehydration, coma and death.

For further information/education on HHNK, check out these website links.

http://www.diabetes.org/living-with-diabetes/complications/hyperosmolar-hyperglycemic.html

http://www.differencebetween.net/science/health/disease-health/difference-between-dka-and-hhnk/

https://emedicine.medscape.com/article/1914705-overview