Hyperosmolar Hyperglycemic State (HHS, HHNS, HHNK) of type 2 Diabetes: Symptoms, Treatment and Risk factors

Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS) is also called Hyperosmolar Hyperglycemic Nonketotic Coma (HHNC), Hyperosmolar Hyperglycemic State (HHS), Hyperosmolar Coma, Hyperosmolar Non Ketotic Coma (HONK), or Nonketotic Hyperosmolar Coma. Whatever name you decide to call it, Hyperosmolar Hyperglycaemic State is a metabolic complication of uncontrolled type 2 diabetes mellitus and usually occurs in elderly patients that do not develop ketosis. Patients present in middle or later life and in most instances with previously undiagnosed diabetes mellitus. Hyperosmolar hyperglycemic state and ketoacidosis are actually two ends of a spectrum and not two distinct disorders.

Table of Contents

Epidemiology of Hyperosmolar Non Ketotic Coma (HONK, HHS, HHNC, or HHNS)

Hyperosmolar Hyperglycemic State is a rare condition that constitutes about 5-10% of hyperglycemic Diabetic mellitus emergencies and it is seen more in elderly people especially those in institutions like old peoples homes. This diabetic complication affects only those with type 2 DM especially those on oral hypoglycemic drugs and having with nephropathy.

Precipitating Factors of Hyperosmolar Non Ketotic State

  1. Myocardial infarction
  2. Stroke
  3. Pneumonia
  4. Sepsis
  5. Consumption of glucose-rich fluids
  6. Concurrent intake of medication such as thiazide diuretics or steroids

HHS Symptoms and Signs (hyperosmolar hyperglycemic state Symptoms)

  1. Symptoms of HHS may occur several weeks before the patients present to the hospital and these symptoms include polyuria
  2. Weight loss
  3. Diminished oral fluid intake
  4. Mental confusion
  5. Lethargy
  6. Coma
  7. On physical examination, there would be severe dehydration – the dehydration is caused by osmotic diuresis that is induced by hyperglycemia and becomes severe when it is not matched by adequate fluid intake
  8. Hypotension
  9. Tachycardia
  10. Altered state of consciousness (Coma)

On presentation, there may be evidence of underlying illnesses such as pneumonia or pyelonephritis and the hyperosmolar state may predispose to having myocardial infarction or arterial insufficiency in the lower limbs or coma in severe cases.

HHS Diagnosis

Diagnosis of HHS is clinical but laboratory tests help to confirm diagnosis when there is high serum blood glucose level in the range of 600- 1200mg/dL and plasma osmolality is usually extremely high (in excess of 330 milliOsmoles).

HHS Diagnosis using Laboratory values. This shows the different changes in Diabetic Ketoacidosis and Hyperosmolar Hyperglycemic State
HHS Diagnosis using Laboratory values. This shows the different changes in Diabetic Ketoacidosis and Hyperosmolar Hyperglycemic State


Laboratory Diagnosis of HHS (Electrolyte changes in HHS)

  1. Sodium (Na+): 155 mmol/L
  2. Potassium (K+): 5 mmol/L
  3. Chloride (Cl): 110 mmol/L
  4. Bicarbonates (HCO3): 25 mmol/L
  5. Urea: 15 mmol/L
  6. Glucose: 50 mmol/L
  7. Arterial pH: 7.35

Treatment of Hyperosmolar Hyperglycemic Syndrome (HHS Treatment )

Many patients having Hyperosmolar Hyperglycemic Non-ketotic Syndrome are extremely sensitive to insulin, therefore the glucose concentration may plummet giving rise to a change in osmolality. This change in osmolality may cause cerebral damage; it is sometimes useful to infuse insulin at a rate of 3 IU per hour for the first 2 to 3 hours and then increasing to 6 U/hour if glucose is falling too slowly.

The standard fluid for replacement is by use of 0.9% physiological saline (please avoid 0.45% saline because rapid dilution of the blood may cause more cerebral damage than a few hours of exposure to hypernatremia). The patient also requires prophylactic anticoagulation as well as identifying and treating the precipitating factor also prevents reoccurrence.

Biochemical Differences between Diabetic Ketoacidosis and HHS

The differences between DKA and HHS may partly can be explained in terms of age and degree of insulin deficiency.

Age: the severe dehydration of hyperosmolar hyperglycaemic state may be related to age since elderly people experience thirst less acutely putting them at risk of becoming dehydrated even without knowing; in addition to this, the mild renal impairment associated with age results in increased urinary losses of fluid and electrolytes in the elderly.

The degree of insulin deficiency: insulin deficiency is less severe in the hyperosmolar hyperglycaemic state compared to Diabetic ketoacidosis because the endogenous insulin levels are sufficient to inhibit hepatic ketogenesis coupled with the fact that glucose production is unrestrained.

HHS Prognosis and Mortality rate

The mortality rate of hyperosmolar hyperglycemic state ranges as high as 20 to 30% and it is mainly caused by advanced age of the patients and the frequency of intercurrent illness. Unlike Diabetic ketoacidosis (DKA), the hyperosmolar hyperglycemia state is not an absolute indication for subsequent insulin therapy and those who survive may do well on diet and oral hypoglycemic agents.