Hypoglycaemia

Question 1

What is the definition of hypoglycaemia

Answer 1

Glucose < 4mmol/L
Paediatrics = <2.5mmol/L
Diabetes = <3.5mmol/L

Question 2

Describe what happens physiologically in hypoglycaemia

Answer 2

1. Low glucose → insulin ↓ + glucagon ↑
   - Reduction in peripheral uptake of glucose
   - Glycogenolysis → ↑ FFAs → enter the beta-oxidation cycle to make ATP (excess become ketones)
   - Gluconeogenesis
   - Lipolysis
2. hypothalamus senses hypoglycaemia → catecholamine release + ACTH → cortisol + GH release

Question 3

What is Wipple’s triad

Answer 3

1. Low glucose
2. Symptoms (adrenergic or neuroglycopaenic)
3. Relief of symptoms upon treatment

Question 4

What are the causes of hypoglycaemia in non-diabetics

Answer 4

Fasting or reactive
Critically unwell
Organ failure i.e. renal failure
Hyperinsulinism
Post-gastric bypass
Drugs
Extreme weight loss
Factitious (i.e. an artefact)

Question 5

What are the causes of hypoglycaemia in diabetics

Answer 5

Medications (inappropriate insulin)
Inadequate CHO intake/missed meal
Impaired awareness (autonomic neuropathy)
Excessive alcohol
Strenuous exercise
Co-existing autoimmune conditions e.g. Addison’s
Renal/liver failure alters drug clearance

Question 6

Which medications are hypoglycaemic

Answer 6

Sulphonylureas (causes endogenous insulin production)
Meglitinides
GLP-1 agents in conjunction with insulin
INsulin
Beta-blockers
Salicylates
Alcohol (inhibits lipolysis)

Question 7

What are the causes of a low insulin and low C-peptide

Answer 7

Hypoinsulinaemic hypoglycaemia
Suggests that something else is causing the hypoglycaemia.
The insulin level is appropriate response to hypoglycaemia which can be caused by:
- Fasting/starvation
- Strenuous exercise
- Critical illness
- Endocrine deficiencies (i.e. hypopituitarism, adrenal failure)
- Liver failure
- Anorexia nervosa

Question 8

What causes high insulin and high c peptide

Answer 8

Hyperinsulinaemic hypoglycaemia
Endogenous insulin production
- Drugs (sulphonylureas - will make the pancreas produce more insulin)
- Islet cell tumours (e.g. insulinoma)
- Islet cell hyperplasia: Beckwith Widemann syndrome, infant of diabetic mothers, nesidioblastosis

Question 9

What are the causes of high insulin and low c peptide

Answer 9

exogenous insulin

Question 10

What are the causes of neonatal hypoglycaemia

Answer 10

Explainable:
- Premature, co-morbidities, IUGR, small-for-gestational-age
- Inadequate glycogen and fat stores
- Should improve with feeding
Pathological:
- Inborn errors of metabolism e.g. MCADD, carnitine disorder, glycogen storage disease, fatty acid oxidation disorder → low insulin, C-peptide, raised FFA, low ketones

Question 11

What are the symptoms of hypoglycaemia

Answer 11

Asymptomatic
Adrenergic:
- Tremors
- Palpitations
- Sweating
- Hunger
Neuroglycopaenic
- Somnolence
- Confusion
- Incoordination
- Seizures, coma

Question 12

Investigations for hypoglycaemia

Answer 12

BM
ECG

Insulin levels (4-6min half life, hepatic clearance)
C-peptide
Drug screen
Autoantibodies
Cortisol/GH
FFAs/blood ketones
Lactate
IGF-2
Carnitine
Ammonia

Question 13

What is the management for hypoglycaemia in adults

Answer 13

A-E
Alert & orientated: oral carbohydrates (Rapid = juice, sweets, glucose/dextrose tablet, glucojuice | long = sandwich) → re-assess after 10-15 minutes

Drowsy/confused with swallow: buccal glucose (hypostop/glucogel/dextrogel)

Drowsy: IM glucagon 1mg

Unconscious or swallow compromised: IV 20% glucose 100ml (10% in separate boluses)

Deteriorating → IM/SC 1mg glucagon (15-20mins)

Question 14

What are the caveats to management of hypoglycaemia

Answer 14

Requires continuous monitoring
Glucagon takes 15-20 mins to mobilise glycogen stores
Glucagon not suitable for liver failure (no glycogen)
Glucagon → rebound hypoglycaemia
Recurrent hypos → hypoglycaemia unawareness