Very low or very high blood glucose levels are the primary causes of diabetic coma occurring in people with diabetes.

There are three types of diabetic coma:

• Diabetic ketoacidosis coma,
• Hyperosmolar coma and
• Hypoglycaemic coma.

Coma is relatively rare in diagnosed diabetes but it is crucial to be aware of the situations that may increase the risk of it occurring (Diabetes.co.uk. 2019).

Diabetic coma is regarded as a medical emergency and requires immediate treatment (BetterHealth 2014; RCNI 2016).

1. Diabetic Ketoacidosis Coma

Diabetic ketoacidosis (DKA) typically occurs in people with type 1 diabetes, though it is possible for it to occur in people with type 2 diabetes (BetterHealth 2014; Cherney 2016). In this instance, a patient will present with very high glucose levels, above 17 mmol/L (Diabetes.co.uk 2019).

This particular form of coma is a consequence of a build-up of chemicals known as ketones. Ketones are strongly acidic and, as a result, increase the blood’s acidity to unsafe levels (BetterHealth 2014)

When there is not enough insulin in circulation, the body is unable to use glucose for energy. Instead, fat is broken down and then converted to ketones in the liver. These ketones build up excessively when insulin remains low (BetterHealth 2014).

A common cause of ketoacidosis is a missed dose of insulin or acute infection in a person with type 1 diabetes. Ketoacidosis can also be considered the first sign that a person has developed type 1 diabetes (BetterHealth 2014; RCNI 2016).

Symptoms

The following should be monitored as a possible symptom of ketoacidosis

• Lethargy;
• Nausea;
• Vomiting;
• Extreme thirst;
• Frequent urination;
• Abdominal pain;
• Drowsiness;
• Disorientation;
• Deep and rapid breathing; and
• Fruity or acetone smell on breath.

(BetterHealth 2014; Diabetes.co.uk 2019).

Treatment

Intravenous fluids, insulin and administration of potassium is the recommended treatment for diabetic ketoacidosis (BetterHealth 2014).

2. Diabetic Hyperosmolar Coma

Diabetic hyperosmolar coma is the result of severe dehydration combined with very high blood glucose levels (also known as hyperglycaemia) (BetterHealth 2014).

This coma may be the result of forgotten diabetes medications such as insulin, infection or illness, or an increased intake of sugary foods . People most at risk are those with type 2 diabetes who have an infection or acute illness and/or have reduced their fluids (BetterHealth 2014).

In the event of high levels of glucose, the kidneys attempt to remove it and in this process, remove water as well. A person suffering a diabetic hyperosmolar coma will not be able to drink enough water to hydrate themselves. They will become dehydrated and require intravenous fluids. Without this, it may lead to a coma for the person (BetterHealth 2014).

This condition develops slowly, over several days to a week - if high blood glucose levels or dehydration is detected and treated early, this coma can be prevented (BetterHealth 2014).

Events that Lead to High Blood Glucose

• Forgetting to take diabetes medications e.g. insulin;
• Infection or illness, such as flu or pneumonia; and
• An increased intake of sugary foods or fruits.

(BetterHealth 2014).

Treatment

The first line of treatment for hyperosmolar coma is intravenous fluids, insulin, potassium and sodium administered as soon as possible (BetterHealth 2014).

3. Diabetic Hypoglycaemic Coma

Hypoglycaemia or low blood glucose levels (below 3.5 mmol/l) can occur if a person on insulin or other diabetes medication takes an extra or increased dose; exercises strenuously without eating food to compensate; reduces their medication; skips a meal or snack; or drinks excessively or drinks alcohol without eating food (BetterHealth 2014; Diabetes.co.uk 2019).

If a person’s blood glucose falls to extremely low levels, the person may become unconscious (hypoglycaemic coma) and in some cases, seizures can occur (BetterHealth 2014).

Symptoms

The key signs and symptoms of hypoglycaemia are:

• Tremor;
• Racing pulse and or heart palpitations;
• Sweating;
• Weakness;
• Intense hunger;
• Confusion; and
• Altered behaviour.

(BetterHealth 2014; RCNI 2016).

Treatment

The first treatment for diabetic hypoglycaemic coma is an injection of glucagon to counteract the effects of insulin or an administration of intravenous glucose (BetterHealth 2014).

Diagnosis of Diabetic Coma

A coma is a medical emergency. A quick and accurate diagnosis may be the key to saving someone’s life.

The following will help to determine the cause of the coma: A medical history; a physical examination; and blood tests (BetterHealth 2014).

First Aid for Diabetic Coma

Take the following steps in the event of diabetic coma in the community:

• Dial triple zero for an ambulance immediately.
• Don’t give the patient anything to eat or drink, as they may choke.
• Turn them onto their side, in the recovery position, to prevent obstruction to breathing.
• Follow any instructions given to you by the operator until the ambulance officers arrive.
• Don’t give them an insulin injection.
• If available, administer 1 mg of glucagon for the reversal of hypoglycaemia.

(BetterHealth 2014; RCNI 2016).

Prevention of Diabetic Coma

The following measures should be taken to decrease the risk of coma occurring:

Know the signs and symptoms of high and low blood glucose; Test blood sugar levels, particularly in the event of illness; Drink alcohol responsibly and avoid after exercise; Be aware of the chance of hypoglycemia at night after exercising (if using insulin or sulfonylureas); and Test for ketones if blood glucose levels are particularly high (type 1 diabetes).

(Diabetes.co.uk 2019)

Conclusion

Education and prevention are the most reliable methods of ensuring that a person with diabetes does not suffer a coma. Diabetic coma is an emergency situation and requires immediate treatment.

Additional Resources

National Evidence Based Guideline For Diagnosis, Prevention and Management of Chronic Kidney Disease in Type 2 Diabetes,  http://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/14d82dbb-d776-40c5-a848-9b22f251514e.pdf

National Evidence Based Guideline For Case Detection and Diagnosis of Type 2 Diabetes, http://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/af2389ea-8f61-4c54-82d6-77ab07f03597.pdf

National Evidence Based Guideline For Patient Education in Type 2 Diabetes, http://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/b9b8789d-c7ba-473d-bd49-0b7d793a0835.pdf

National Evidence Based Guideline For Blood Glucose Control in Type 2 Diabetes, http://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/659c89a3-dcc2-4a2e-86e5-cc1d09956c60.pdf

National Evidence Based Guideline For the Primary Prevention of Type 2 Diabetes, http://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/b1126d58-2763-403a-bd2d-44a241bb9189.pdf

Multiple Choice questions

References

• BetterHealth 2014, ‘Diabetic Coma’, viewed 9 August 2019, https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/diabetic-coma
• Cherney, K 2016, ‘Understanding and Preventing Diabetic Coma’, Healthline, viewed 12 August 2019, https://www.healthline.com/health/understanding-and-preventing-diabetic-coma#emergency-care
• Diabetes.co.uk 2019, ‘Diabetic Coma’, viewed 9 August 2019, https://www.diabetes.co.uk/diabetes-complications/diabetic-coma.html
• RCNI 2016, ‘Emergency Treatment for Diabetes’, viewed 12 August 2019, https://rcni.com/hosted-content/rcn/diabetes/emergency-treatment-diabetes

(Answers: a, d, a.)