By Dr Milton Lum
coma is a state of unconsciousness in which
a person does not respond and cannot be
awakened. Although the person is alive, there
is minimal brain activity. The eyes will be closed,
without any response to sound or pain. There is an inability
to communicate, lack of voluntary movements and reduced
basic reflexes like coughing and swallowing. There may be the
ability to breathe, although some require assistance from a
ventilator. The Glasgow Coma Scale is used to assess the level
of consciousness. It involves an assessment of eye movement,
verbal response to a command, and voluntary movements
in response to a command. The total score is 15 and most
people in a coma have a total score of eight or less. A coma in
diabetics is usually due to very low or very high blood glucose
levels. The former is called a hypoglycaemic coma and the
latter, a hyperglycaemic coma.
Hypoglycaemic Coma
Hypoglycaemia, a condition in which the blood glucose
level is lower than normal, is due to an imbalance between
glucose supply, glucose utilisation and current insulin levels.
The condition is the most common side effect of insulin and
sulphonylureas usage in diabetes treatment. Type 1 diabetics
can experience about two episodes of mild hypoglycaemia
per week. The annual prevalence of severe hypoglycaemia
in unselected populations, has been reported at 30-40%
consistently in several large studies.
Severe hypoglycaemia is less common in insulin-treated type
2 diabetes, but it is still a significant clinical problem. Patients
with insulin-treated type 2 diabetes are more likely to require
hospitalisation for severe hypoglycaemia than those with
type 1 diabetes. A hypoglycaemic
coma is more likely to occur if
there is inadequate blood glucose
monitoring; a large insulin or
sulphonylurea overdose; irregular
meals; poor appetite; vomiting;
increased exercise; impaired
liver or renal function; and/or
alcohol consumption. Medicines
like warfarin, salicylates, fibrates,
sulphonamides (including
cotrimoxazole), NSAIDs (non-steroidal anti-inflammatory
drugs) and SSRIs (selective serotonin reuptake inhibitors)
can also trigger hypoglycaemia.
The symptoms vary, but it has to be considered in any
diabetic who is acutely unwell, drowsy, unconscious, unable
to co-operate and/or presents with aggressive behaviour
or seizures. Every diabetic with hypoglycaemia should be
treated without delay to return the blood glucose levels
to normal range. A quick-acting carbohydrate should be
followed up by giving a long-acting carbohydrate, either
as a snack or as part of a planned meal. A blood glucose
measurement will be taken to confirm hypoglycaemia. If
measurement is difficult, e.g. in someone with a seizure,
then treatment should not be delayed.
After acute treatment, a determination will be made as to
whether the hypoglycaemia is likely to be prolonged, i.e.
as a result of long acting insulin or sulphonylurea, in which
case a continuous infusion of dextrose will be necessary to
maintain blood glucose levels. To prevent any hypoglycaemic
coma, it is the practice to treat any blood glucose less
than 4 mmol/L.
Diabetic Ketoacidosis
Diabetic ketoacidosis (DKA) occurs when there are very high
blood glucose levels (typically above 17 mmol/L) and high
ketone levels.
triggered by illness, with infection the most common, leading
to reduced fluid intake. As the blood glucose levels increase
in HHS, the body tries to get rid of the excess glucose by
increased urinary volume. Later, the urine becomes
concentrated as dehydration sets in with increased thirst.
Eventually, seizures and HHNC occur, and death results if
HHNC is untreated. HHS may take days or weeks to develop.
The features of HHS include dry, parched mouth; extreme
thirst; warm, dry skin that does not sweat and high fever;
and later, confusion; loss of vision; weakness on one side
of the body; seizures and coma. The blood glucose levels are
typically above 33 mmol/L.The treatment of HHS includes
vigorous rehydration; maintenance of electrolyte balance;
correction of hyperglycaemia; treating any underlying
condition; and supporting cardio-respiratory, kidney and
central nervous system function.
Prevention Measures
It occurs when there is an inability to use blood glucose
because there is insufficient insulin. Instead, the body breaks
down fat as an alternative source of energy. This causes a
build-up of potentially harmful by-products called ketones.
The common triggers of DKA include infections like urinary
tract infection, gastroenteritis, influenza or pneumonia;
missed insulin due to problems with the injector; recent
change in the treatment regime; and undiagnosed diabetes,
usually type 1. Other less common triggers include usage
of illegal drugs and certain medicines like steroids, as well
as heart attacks, strokes and binge drinking.
DKA is common in type 1 diabetics and can occasionally
affect type 2 diabetics. It can also occur in those previously
not diagnosed with diabetes. It is most common in children
and young adults. The features of DKA include passing large
amounts of urine, feeling very thirsty, nausea, vomiting,
tiredness, shortness of breath and disorientation, followed
by loss of consciousness and coma. Treatment includes
insulin, rehydration with intravenous fluids, and correction of
mineral deficits like potassium. Complications of DKA like
acute kidney failure, brain oedema and acute respiratory
distress are treated accordingly.
Hyperosmolar Hyperglycaemic Non-Ketotic Coma
Hyperosmolar hyperglycaemic state (HHS) occurs in poorly
controlled type 1 or 2 diabetics, but is more common in
type 2 diabetics. It was previously termed hyper-osmolar
hyperglycaemic non-ketotic coma (HHNC). The terminology
was changed because coma is found in less than 20% of
patients with HHS. HHS is less common than DKA. It is usually
The features of HHS and DKA overlap in as many as one third
of cases and are observed simultaneously. This suggests that
these two states of uncontrolled diabetes differ only with
respect to the magnitude of dehydration and the severity of
acidosis. The following measures can prevent hypoglycaemic
and hyperglycaemic diabetic comas:
• Ensure diabetes is well controlled
• Keep appointments with the doctor
• Be aware of the symptoms of high and low blood glucose
• Check blood glucose levels more frequently when ill
• Continue taking insulin and sulphonylureas when ill
• Keep oneself well hydrated
• Consume alcohol in moderation, or better still, avoid it
altogether, especially after strenuous exercise
• Beware of hypoglycaemia at night following exercise, if
taking insulin or sulfonylureas
• Check for ketones if blood glucose levels are high in type
1 diabetes. In general, a blood glucose of 11 mmol/L or
more is indicative of an increased risk of DKA.
The take home message is prevention is better than cure.
Dr. Milton Lum is a Member of the Medical Defence Malaysia
Board. The information in this article is for educational and
communications purposes only and should not be construed
as personal medical advice.