Hyperglycemic Hyperosmolar Nonketotic Syndrome

Also called Hyperosmolar Nonketotic State (HNS); Hyperosmolar Hyperglycemic Syndrome; Diabetic Hyperosmolar State; Hyperosmolar Hyperglycemic Nonketotic coma; Hyperosmolar Coma or Nonketotic Hypertonicity.

Though rare, this is another life threatening acute complication and one needs to know about it.

This condition is more usual in Type 2 diabetics than Type 1 and about 30% of cases seen occur in people who have advanced diabetes that is undiagnosed.

It, like ketoacidosis , is caused by extremely high blood glucose levels, often 33.3 mmol/L (600mg/dL) or more. The difference is that excessive ketones are not present.

It is thought that these diabetics still produce enough insulin to prevent the liver from resorting to burning fat, thus producing ketones, but insufficient insulin, or there is too high insulin resistance, to prevent the blood glucose from soaring.

When the body tries to get rid of the glucose by passing it out in the urine it leads to fluid loss and increased thirst - much the same symptoms as occur before a diabetes diagnosis.

When for some reason the person is unable to drink enough fluids to re-hydrate themselves they become dehydrated and HHNS occurs.

Generally this occurs when there is constant vomiting, diarrhoea or inability to get to a source of liquid as in the case of injury or severe illness where outside help is unavailable.

Some people, such as many elderly, have an impaired ability to recognise thirst. They seem to have an 'altered' sense of being thirsty, so do not drink enough.

Unfortunately elderly diabetics living in a nursing home often do not receive the attention they need to address this problem, which is probably why HHNS is so frequently found in such patients.

Unlike ketoacidosis, HHNS comes on slowly, over a number of days, and can be missed if sufficient attention is not being paid to the patient. If a severe loss of body water occurs it can result in shock, coma and death.

Death rates as high as 50% have been quoted.

What triggers HHNS:-

1. Infection.
2. Kidney Disorders.
3. Heart attack.
4. Medication such as diuretics, heart medication, steroids or beta blockers.
5. Stress, leading to hormonal changes and forgetfulness (forget meds.)
6. Excessive alcohol intake which leads to increased urination & fluid loss.
7. Chronic illness.
8. Bleeding ulcer.
9. Too little insulin or oral anti-diabetic agents.
10. Recent surgery.

The symptoms that you need to look out for are:-

1. BG over 33.3mmol/L (600mg/dL)
2. No ketones in your urine despite high BG's.
3. Increased thirst, with dry mouth
4. Increased urination
5. Skin is hot but you do not sweat
6. Headache
7. Tiredness - feeling very sleepy
8. Temperature is over 38deg C (100.4 degrees Fahrenheit)
9. Systolic blood pressure is less than 100
10. Loss of vision
11. Confusion and possible hallucinations
12. Paralysis, or weakness on one side of the body
13. Inability to speak properly

If any of these symptoms are present a doctor should be consulted.

Any Bg level over 27.8mmol/L (500mg/dL) should in any case be considered an emergency and the patient taken to hospital immediately.

The doctor will order blood tests to confirm a diagnosis of HHNS.

To get a positive diagnosis the results must show:-

1. Serum osmolality (concentration of particles) of 320 mOsm/kg
2. Plasma glucose level greater than 33.3 mmol/L (600 mg/dL)
3. Intense dehydration shown by elevated serum sodium levels.
4. No ketoacidosis
5. PH of 7.3
6. HCO3 - greater than 15 mEq/L


The patient will be hospitalised where they will be put on a drip to containing fluids to correct the dehydration and restore electrolytes. Insulin may be given until such a time as BG's are back within the normal range.

If the HHNS is due to some underlying illness it will be necessary to treat that as well.

Recovery with the correct treatment can be quite rapid, though some of the symptoms may take a week or so to disappear.


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