Hypoglycaemia Flashcards
What is the definition of hypoglycaemia?
Hypoglycaemia is defined as BSL < 4mmol/L
What are the symptoms of hypoglycaemia?
Symptoms can be divided into:
- Adrenergic (autonomic): pallor, sweating, shaking, palpitations, anxiety. Note: adrenergic response is reduced during sleep, post-exercise, or alcohol consumption.
- Neuroglycopenic (due to altered brain function): hunger, difficulty concentrating, confusion, inappropriate behaviour, loss of consciousness, seizures
When do patients get symptoms of hypoglycaemia?
Patients can experience symptoms at BSLs > 4mmol/L or < 4mmol/L.
Patients are more likely to have symptoms at lower concentrations if there have been recent episodes of hypoglycaemia - ie, body becomes ‘tolerant’ to it.
Symptoms occur at higher concentrations if hypoglycaemic episodes are infrequent and/or there is suboptimal glycaemic control ie, sugars run a bit high at baseline.
Patients can be asymptomatic particularly in patients who have had diabetes for >10 years (hypoglycaemic unawareness)
What are some common acute precipitants of hypoglycaemia?
- Variation in carbohydrate content of food intake eg, fasting, stopping an enteral feed
- Stopping hyperglycaemia-inducing drugs eg, glucocorticoids
- Suppression of glucose production in the liver by alcohol
- Vigorous and/or prolonged exercise. Risk of hypoglycaemia is increased after exercise for at least >12 hours - can result in nocturnal hypoglycaemia. However, the response of BSL to exercise varies so it is individualised to the patient.
- Incorrect dose or administration of insulin or long-acting sulfonylurea
Some are some risk factors for hypoglycaemia?
- Previous severe hypoglycaemia
- Hypoglycaemic unawareness
- Duration of diabetes
- Treatment with insulin or a long-acting sulfonylurea (eg, glibenclamide, glimepiride)
- Increasing age
- Pregnancy and while breastfeeding
- Cognitive impairment
- Kidney impairment
- Liver failure
- Primary gastrointestinal disease with malabsorption eg, coeliac disease
- Primary deficiencies in hormones that raise blood glucose concentrations eg, cortisol (hypopituitarism, adrenal cortical failure), growth hormone (isolated growth hormone deficiency)
- Previous bariatric surgery
- Recent weight loss
What is hypoglycaemic unawareness?
Occurs when the threshold for development of adrenergic (autonomic) symptoms is close to, or lower than, the threshold for neuroglycopenic symptoms. Thus, the characteristic adrenergic symptoms that alert a patient of the onset of decreasing BSLs are absent, and the first sign of hypoglycaemia is confusion or loss of consciousness.
Hypoglycaemic unawareness is associated with severe hypoglycaemia.
Who is at risk of hypoglycaemic unawareness?
More common in patients with T1DM especially if >10 years duration.
It may also occur in patients with T2DM or other types of diabetes, especially those treated with insulin or a sulfonylurea.
Hypoglycaemic unawareness may follow repeated episodes of short-duration hypoglycaemia - these episodes impair the adrenergic responses to subsequent hypoglycaemia.
Is hypoglycaemic unawareness reversible?
What should happen to the HbA1c targets?
Driving and occupational implications?
Hypoglycaemic unawareness and defective counter-regulatory hormone response (associated with hypoglycaemia unawareness) are potentially reversible. Strict avoidance of hypoglycaemia for periods of 2 days - 3 months have been associated with improvement with recognition of severe hypoglycaemia, counter-regulatory hormone response or both.
Patients with hypoglycaemia should have their HbA1c targets individualised accordingly ie, may need slightly higher targets.
Patients with hypoglycaemic unawareness should have their fitness to drive assessed and monitored by an experienced diabetes specialist. Occupational implications should also be considered, particularly if the patient is required to operate heavy machinery and equipment.
How do you define severe hypoglycaemia?
Management of severe hypoglycaemia?
If severe (patient unable to treat themselves due to confusion or LOC):
- Confirm BSL if it will not delay treatment
- Glucagon injection or IV glucose infusion depending on availability § Glucagon injection:
- Glucagon 1mg IM or subcut.
- Unconscious adult patients usually start to respond within 6 minutes. If no response, the patient may have insufficient stores of glucose in the liver (eg, severe liver disease, chronic malnourishment) - IV glucose will be needed. If IV glucose not available, give second glucagon dose 20minutes after the first.
- Glucagon can cause nausea + vomiting as the patient regains consciousness
- IV glucose:
- Ideally use secure cannula in cubital fossa. Infusion in hand veins can cause superficial thrombophlebitis especially at higher glucose concentrations.
- Give dextrose 10% 150-200mL over 15 minutes OR dextrose 20% 75-100mL over 15 minutes OR dextrose 50% slow IV injection
- Do NOT give 50% IV to children or adolescents as it can cause hyperosmolality and subsequent death
- Use 50% dextrose with extreme caution because extravasation can cause potentially serious necrosis.
- Adult patients usually regain consciousness within minutes of infusion. Measure BSL at 10-15minutes after infusion and repeat the dose if BSL remains <4mmol/L.
- If the adult is conscious and able to swallow, give longer-acting carbohydrate to prevent recurrence.
- Subsequent monitoring: measure BSLs every 1-2hrs for 4 hours, then resume usual testing regimen for patients with T1DM, or for patients with T2DM continue testing more frequently depending on the patient’s antihyperglycaemic regime.
- Glucagon 1mg IM or subcut.
Prevent future episodes - need a multidisciplinary diabetes team
- Determine possible causes
- Review insulin/OHG regime
- Insulin should never be stopped in T1DM
- Dietary review
- Diabetes nurse educator - education around preventing and managing hypoglycaemia if required.
- Patient information sheet from National Diabetes Services Scheme (NDSS) website.
Driving and occupational hazard:
- Patients who have had an episode of severe hypoglycaemia must not drive until they have been assessed and recommended for resumption of driving by their specialist. Laws around reporting episodes of severe hypoglycaemia vary in different states.
- Patients with hypoglycaemic unawareness should have their fitness to drive assessed and monitored by an experienced diabetes specialist.
- Occupational implications should also be considered, particularly if the patient is required to operate heavy machinery and equipment.
How do you define non-severe hypoglycaemia?
Management of non-severe hypoglycaemia
If non-severe (patient conscious, able to accept or self-administer oral treatment):
- Confirm BSL if able
- PO glucose ~15g equivalent
- Repeat PO glucose if BSL <4.0 after 10-15min
- When BSL increases to normal, give longer acting carbohydrate eg, sandwich, fruit, yoghurt.
Prevent future episodes - need a multidisciplinary diabetes team
- Determine possible causes
- Review insulin/OHG regime
- Insulin should never be stopped in T1DM
- Dietary review
- Diabetes nurse educator - education around preventing and managing hypoglycaemia if required.
- Patient information sheet from National Diabetes Services Scheme (NDSS) website.
Driving and occupational hazard:
- Patients who have had an episode of severe hypoglycaemia must not drive until they have been assessed and recommended for resumption of driving by their specialist. Laws around reporting episodes of severe hypoglycaemia vary in different states.
- Patients with hypoglycaemic unawareness should have their fitness to drive assessed and monitored by an experienced diabetes specialist.
- Occupational implications should also be considered, particularly if the patient is required to operate heavy machinery and equipment.
How does alcohol cause hypoglycaemia?
Why is alcohol induced hypoglycaemia particularly dangerous?
Alcohol inhibits glucose production by the liver.
Excessive alcohol consumption may cause hypoglycaemia in patients with T1DM. But severe hypoglycaemia can occur with ANY alcohol consumption in combination with inadequate carbohydrate intake or other acute precipitants of hypoglycaemia.
This situation is particularly dangerous when the patient is intoxicated and unable to recognise the symptoms or hypoglycaemia.
Management of sulphonylurea-induced hypoglycaemia
If hypoglycaemia occurs, increase frequency of BSL monitoring until it increases to normal.
If patient is taking long-acting sulfonylurea and/or has CKD, hypoglycaemia may be prolonged and monitoring should be continued for >24hrs.
If the patient is taking insulin + sulfonylurea, the hypoglycaemia can be more pronounced and monitoring should be continued for >24hrs.
