Diabetic coma is a dangerous condition that can lead to unconsciousness and even death. Diabetic coma may affect 2% to 15% of all diabetics at least once in their lifetime and the condition that most commonly causes the coma is severe hypoglycaemia or low blood sugar.
There are three main causes of coma in people with diabetes: diabetic ketoacidosis, severe hypoglycaemia and hyperglycaemic hyperosmolar state. However, despite the increased prevalence of diabetes across the globe, improved diagnosis and early treatment of these causative conditions has lessened the risk of death due to diabetic coma.
A glucometer, for example, can detect high or low blood sugar in an unconscious diabetic patient within seconds and this can be confirmed in the laboratory within an hour. Furthermore, due to the widespread warnings and knowledge regarding the possibility of the three conditions, most patients are brought to an emergency unit before the onset of coma.
The three causes of diabetic coma
If an individual’s sugar level in the blood and the brain drops to below 3.5 mmol/l, they are at risk of losing consciousness and falling into a diabetic coma. This risk is greater if an excess dose of insulin or other anti-diabetic medications has been taken, if alcohol is in the person’s body while they are hypoglycemic, or if vigorous exercise has depleted the body’s supply of glycogen.
Diabetic ketoacidosis (DKA)
This condition is more common among people with type 1 diabetes or those with type 2 diabetes who are taking insulin. If there is shortage of insulin, the body fails to use the glucose in the blood for energy and instead fats are broken down in the liver to form acidic compounds called ketones. These ketones build up in the body causing DKA. The condition may occur due to a missed or inadequate insulin dose, acute infection, major injury or surgery.
Hyperglycaemic hyperosmolar state (HHS)
This condition is characterized by severe dehydration, high blood glucose and high blood osmolarity. Common causes of HHS are a missed insulin dose, acute infection or injury, and a heavy food or sugar intake. Unlike with DKA, a coma caused by HHS develops slowly, over several days or weeks.
Reviewed by Sally Robertson, BSc