Definitions
Hypoglycaemia is a blood glucose level (BGL) low enough to cause signs and/or symptoms of impaired brain function and neurogenic response. It cannot be defined by a specific BGL as thresholds for specific brain responses to hypoglycaemia occur across a range of BGLs and can be influenced by the presence of alternative fuels such as ketones or lactate.
- Neurogenic symptoms are perceived at a BGL < 3.0 mmol/l, which in older children and adults triggers a search for food or assistance.
- Cognitive function is impaired at a BGL concentration < 2.8mmol/l.
- A BGL < 2.6 mmol/l is generally regarded as a level at which prompt investigation and treatment is required regardless of the presence of symptoms.
Critical
BGL < 2.6 mmol/L
Immediate treatment required regardless of symptoms
Warning
BGL < 2.8 mmol/L
Cognitive impairment begins
Neurogenic
BGL < 3.0 mmol/L
Symptoms trigger food-seeking behavior
Causes
Any Age
- Complication associated with insulin dependent diabetes mellitus
- Other illness (e.g. sepsis, congenital heart disease, tumour, liver failure, malaria)
- Drug related: insulin, sulphonylureas, ethanol, methanol, salicylates, beta blockers, chemotherapy
Neonate < 48-72 hours
- Prematurity
- IUGR
- Perinatal asphyxia
- Hypothermia
- Sepsis
- Respiratory distress
- Diabetic mother
- Macrosomia
- Syndrome (e.g. Beckwith-Wiedemann)
- Pancreatic dysfunction
Neonate - 2 years
- Congenital hyperinsulinism (most common cause of persistent hypoglycaemia < 2 yrs)
- Inborn errors of metabolism
- Congenital hormone deficiencies (e.g. growth hormone deficiency)
Child
- Idiopathic ketotic hypoglycaemia
- Hypopituitarism
- Growth hormone deficiency
Adolescent
- Insulinoma
- Adrenal insufficiency
- Eating disorder
Clinical Features
Symptoms of hypoglycaemia
- Palpitations, tremor, anxiety, sweating, hunger and abdominal pain, paraesthesia, weakness, nausea and vomiting, headache
- Severe hypoglycaemia - lethargy, irritability, uncharacteristic behaviour, hypothermia, confusion, coma, seizures
- Neonate <48 hrs - pallor, sweating, apnoea, tachypnoea, hypotonia, jitteriness, poor feeding, high pitched cry
Signs of hypoglycaemia
- Altered conscious state and seizures
- Fever or hypothermia
- Finding related to underlying diagnosis
- Hepatomegaly and/or hypotonia (inborn error of metabolism)
- Poor growth and nutrition
- Dysmorphism (syndrome)
Investigations
Notes:
- A capillary glucometer reading is unreliable at low readings; hence it is important to confirm that true (laboratory) BGL is <2.6 mmol/L.
- A key clinical practice point is to take blood and next urine for ketones at the time of hypoglycaemia and before treatment with glucose (although this should not significantly delay management). The presence or absence of ketones at the time of hypoglycaemia is diagnostically crucial to aid diagnosis and subsequent management.
- First presentation or severe hypoglycaemia should be investigated. Infants <48 hrs of age who respond appropriately to enteral feeds are unlikely to need extensive investigations.
- Children who present with hypoglycaemia and have not had investigations carried out at the time of hypoglycaemia may require a controlled fast to help make a diagnosis.
Hypoglycaemia screen:
| Sample |
Tests |
| Venous gas |
|
| Blood |
- Glucose
- Ketones (B hydroxybutyrate)
- Lactate
- Free fatty acids
- Carnitine / Acylcarnitine
- Ammonia
- Cortisol
- Insulin & C-peptide
- Growth hormone
- Amino acids
- Urea and electrolytes
- Liver function tests
- Full blood count
- Blood culture
- Alcohol/salicylate level
|
| Urine |
- Glucose
- Ketones
- Reducing substances
- Amino and organic acids
- Toxicology screen
|
If sampling is difficult, the most important tests to collect at the time of hypoglycaemia are:
- Blood glucose
- Ketone level
- Blood gas
- Insulin level
- C-Peptide
- Cortisol
- Lactate
- 1st Urine passed
Management of hypoglycaemia (BGL < 2.6 mmol/l)
Note:
In a child with hypoglycaemia associated with diabetes mellitus, follow diabetes guidelines. The guidelines below are for management of hypoglycaemia in a child not known to have diabetes mellitus.
- Assess and stabilise patient using ABCDE framework
- Confirm BGL < 2.6 mmol/l - ensure lab glucose is sent but do not delay treatment awaiting results
- Collect blood and urine sample for hypoglycaemia screen
- If patient is conscious and non-drowsy:
- <1 year old: give milk feed
- >1 year old: give oral hypoglycaemia treatment
- 5 - 20 g of fast acting carbohydrate (approx. 0.3g/kg)
- e.g. glucose gel/tablets, fruit juice/lucozade
- If patient is drowsy or unconscious:
- IV access:
- IV bolus 10% glucose 2 ml/kg
- No IV access:
- IM glucagon:
- Neonate: 0.03 - 0.1 mg/kg
- ≤ 25 kg: 0.5 mg
- > 25 kg: 1.0 mg
- If following initial treatment child is unable to recommence feeds or remains unwell:
- Start IV glucose infusion using 10% glucose/0.9% sodium chloride solution at rate of 2.4-4.8 ml/kg/hr (equivalent to giving 4-8 mg/kg/min dextrose)
- Recheck capillary BGL at 10 minute intervals until BGL is stable at >3 mmol/l
- If BGL remains below 2.6 mmol/l:
- Repeat IV bolus glucose 10% 2 ml/kg
- Increase IV glucose infusion rate to 6 ml/kg/hr 10% glucose/0.9% sodium chloride (or 10 mg/kg/min dextrose)
- If BGL remains low, increase concentration of glucose in IV fluids