The possibility of hypoglycaemia should be considered with every unconscious patient with diabetes, especially with type 1 diabetes.
To avoid hypoglycaemic attacks the dosing of insulin and other antidiabetic drugs (particularly sulphonylureas and glinides) should be checked every time the patient has
symptoms of hypoglycaemia
low plasma blood sugar levels (< 4 mmol/l) in home tests. Low values at night are particularly dangerous.
Criteria for hypoglycaemia
Low plasma glucose concentration (< 4 mmol/l).
Symptoms indicating hypoglycaemia (may be absent, see below)
The symptoms disappear after giving glucose.
Classification of hypoglycaemia
Mild hypoglycaemia (plasma glucose < 3.9 mmol/l): low blood glucose level which is treated by the patient with fast carbohydrate or by reducing the dose of rapid-acting insulin before the meal
Significant hypoglycaemia (plasma glucose < 3.0 mmol/l): clinically significant low blood glucose level in self-measurement or in continuous monitoring (for at least 15 minutes) or measured in a laboratory
Severe hypoglycaemia: cognitive functioning weakened, and the assistance of another person is required for the management of hypoglycaemia.
The adrenergic symptoms of hypoglycaemia
Heart palpitation
Sweating
Hunger
Tremor of hands
Note that these symptoms may disappear with the duration of diabetes or if the HbA1c concentration is low and the patient has had repeated hypoglycaemic attacks. In the latter case, increasing blood glucose levels for some months may restore the warning symptoms.
If the blood glucose level has been high for a long period, some patients may develop symptoms of hypoglycaemia even when the blood glucose level is normal. This may be partly due to physiological adaptation, which is correctable by improving the glucose balance.
Neuroglucopenic symptoms
Signs of severe hypoglycaemia!
Headache
Confusion
Visual disturbances, especially double vision
Behavioural and personality disturbances
Convulsions and unconsciousness
Patients at risk
The risk of hypoglycaemia is greatest in patients with (type 1) diabetes who
have HbA1c values < 53 mmol/mol (< 7%) and who lack symptoms of hypoglycaemia
have low nocturnal blood sugar levels (the morning fasting level can even be high)
exercise actively and irregularly
neglect their treatment, in particular because of alcohol misuse
have previously had serious hypoglycaemias
have other medications that can possibly mask the symptoms of hypoglycaemia
have a significant renal failure (elimination of insulin slowed down).
Remember treatment of the elderly with sulphonylureas and insulin as a risk factor.
Deficiency of cortisol production and hypothyroidism predispose the patient to hypoglycaemia: remember to suspect them when there is recurrent hypoglycaemia.
Treatment
Mild symptoms suggesting hypoglycaemia should be treated with 10-20 g of rapidly absorbed carbohydrates. If the symptoms have not disappeared after 10 minutes another similar snack should be taken. Recommended snacks include
4 tablets of glucose (10 g)
1 dl (half a glass) of fruit juice
1 table-spoon of honey
1 fruit
1 dl of soft drink with sugar
3-5 pieces of sugar
syrup or strong sugar solution (10 lumps of sugar in warm water) administered on the oral mucosa.
In severe hypoglycaemia inject one ampoule of glucagon (1 mg) subcutaneously or intramuscularly as per the package instructions. The dose is the same for adults and children weighing over 25 kg.
For unconscious patients or patients with convulsions the best treatment is a 10% glucose solution rapidly infused until the patient reaches consciousness. A glucagon injection can be given as first aid. An unconscious patient must not be forced to drink, however, honey or strong sugar solution can be administered orally by spoon if there is no other treatment available.
Further treatment
The medication and injection technique of the patient with diabetes must be checked and the reason for hypoglycaemia investigated.
If the patient is confused, intoxicated or in bad condition after the glucose level is corrected, he should be put under hospital observation to avoid recurrence of hypoglycaemia.
After follow-up the patient can be discharged if his/her condition is good and his/her ability to recognize and treat hypoglycaemia is considered sufficient. The insulin dose should be reduced. An additional appointment with the doctor or diabetes nurse should be arranged so that the reasons for hypoglycaemia can be found and the treatment controlled. The patient needs clear instructions. The patient's fitness to drive should be assessed (consult local guidance).
The patient is instructed to carry e.g. glucose pastilles or juice at all times. An ampoule of glucagon should be kept nearby in case of need.
The effect of sulphonylureas is long lasting. The hypoglycaemias caused by sulphonylureas should be observed for at least 24 hours.
A small child should always be put under hospital observation and the avoidance of further episodes discussed with the parents.
With ultra-long acting insulin analogues (degludek and glargine 300 U/ml), there is less nocturnal hypoglycaemia. Continuous tissue glucose monitoring and/or continuous subcutaneous insulin infusion may be suitable to some of the patients who suffer from recurrent hypoglycaemia.
If the patient does not regain consciousness despite normalization of blood glucose, an emergency referral to hospital must be made. This could be a case in
brain damage due to hypoglycaemia (rare) or
another aetiological explanation for unconsciousness.