HHNS is Hyperosmolar Hyperglycemic Nonketotic Syndrome.

HHNS or HNS is Hyperosmolar hyperglycemic nonketotic syndrome. It is a diabetes complication that occurs in dehydration and hyperglycemia. According to CDC, the blood sugar is usually greater than 600-800mg/dl. This increase in blood glucose is accompanied by increase in the osmolality of the blood, which means that more of other chemicals are also present in the blood. Other symptoms are severe dehydration, loss of consciousness and eventually, coma. This usually happens in type 2 diabetic hyperglycemia because there is still circulating insulin in the blood, making the blood free of ketones. Up to 50% of patients who get this diabetes complications die, so its mortality rate can be as high as 50%. HNC is rare and occurs mostly in patients over 65years of age.

Causes of HHNS

The following are the causes of Hyperosmolar hyperglycemic nonketotic syndrome:

  • Hyperglycemia – Prolonged hyperglycemia or high blood sugar can lead to dehydration. This happens because the blood pulls water from the cells in attempt to dilute the blood that has too much glucose. The cells end up losing water and become too dehydrated.
  • Dehydration then  accompanies the hyperglycemia. Dehydration by itself may also precipitate hyperglycemia because the concentration of glucose in the blood increase because water decreases in the blood.
  • Medications that cause increase in blood sugar, like steroids
  • Diuretics, because they pull water away from the blood and cause dehydration.
  • Age –usually greater than 60 years of age and may be because the older generation is more likely to be dehydrated.
  • Stress.
  • Acute illness like stroke, heart attack or pneumonia.
  • Untreated type 2 diabetes.
  • Loss of sense of thirst, which can result in dehydration
  • Chronic illness
  • Institutionalization
  • Surgery
  • Consumption of too much glucose

Prevention of HHNS

Prevention of hyperosmolar hyperglycemic nonketotic syndrome is achieved by:

  • Blood glucose monitoring and blood sugar control
  • Diabetes education
  • Avoiding dehydration
  • Taking prescribed medication
  • Attention to elderly patients with diabetes
  • Exercise
  • Diabetic diet


Treatment of HHNS

Hyperosmolar hyperglycemic non-ketotic syndrome is treated by fluid and electrolyte replacement to reduce and eventually resolve dehydration. A level of fluid replacement has to be achieved before insulin therapy can begin.

IV rapid-acting insulin or short-acting insulin is slowly dosed, up to 48 hours, to gradually reduce hyperglycemia. Reduction of blood sugar has to be gradual. If the blood sugar is reduced rapidly, it can cause the brain to swell and can result in cerebral edema.


Symptoms of HHNS

The following symptoms may appear in patients with Hyperosmolar hyperglycemic nonketotic syndrome:

  • Dehydration
  • Blood sugar higher than 600mg/dl
  • No ketones in urine because there is some insulin available in the body, which prevents the making of ketones.
  • Acid does not accumulate in blood
  • Sugar in urine.
  • Urine decreases with time because the blood is too concentrated and the filtration of fluid by the kidney is reduced.
  • Blood volume decreases because of dehydration.
  • It is difficult for blood to reach the tissues because the blood volume is reduced. This results in poor tissue perfusion.
  • Severe dehydration
  • Urine chemicals remain in blood because the Kidney is not removing them. This is called azotemia.
  • Swelling in the brain can occur if the blood sugar drops too quickly
  • Central nervous system is affected and this can result in the following symptoms:
  1. Hallucinations where the patient can see, hear or smell things that do not exist.
  2. Patient may be unable to speak, this is called aphasia.
  3. The patient's eyes may be unable to focus because the eyes move in different directions, this is called nystagmus .
  4. The patients visual field may reduce to half and this is called hemianopsia.
  5. There may be one-sided body weaknes, this is called hemiplegia.
  6. Loss of sensation on one side of the body and this is called hemisensory.
  • Seizures.
  • Finally coma which is a diabetic coma.



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