Nonketotic hyperosmolar coma is a life threatening metabolic derangement that can develop in people with diabetes mellitus, usually due to illness, infection or failure to monitor blood glucose levels.

The onset of this type of coma can be gradual and difficult to recognise and treat. The condition is more common among people with type 2 diabetes rather than type 1 diabetes and in older rather than younger individuals.

Symptoms

The symptoms of hyperosmolar hyperglycaemic coma include:

• Hyperglycemia
• Lethargy and general weakness that may progress to exhaustion and even cause collapse
• Features of severe dehydration due to hyperglycaemia such as increased thirst, parched and dry mouth and sunken eyes
• Confusion and sleepiness
• Hallucinations
• Increased heart rate
• Fever
• Convulsions

Pathophysiology

A relative deficiency in insulin levels caused by mismanagement of diabetes causes a rise in blood sugar levels. This triggers the kidneys to remove some of the glucose through urination, causing dehydration and more concentrated or hyperosmolar blood. This concentrated blood begins to draw water form other organs such as the brain and kidneys.

Diagnosis and treatment

Diagnosis is made though clinical examination of patient's symptoms and history of complications and risk factors. Blood sugar levels usually need to be above 600 mg/dl and serum osmolarity above 320 mOsm for a diagnosis to be made.

Treatment includes rapid administration of insulin and fluids to normalize blood sugar levels and correct dehydration. Fluids should be given at least 30 to 60 minutes before insulin. Electrolytes such as sodium, potassium, magnesium and phosphate may be replaced as needed. Some patients may require antibiotics if infection is present.