Hypoglycaemia

NICE BNF Treatment summaries. Hypoglycaemia.

JBDS 01 The Hospital Management of Hypoglycaemia in Adults with Diabetes Mellitus. Last revised: Jan 2023.

Article Last Updated:23/10/2025

Background Information

Definition

Hypoglycaemia is defined as blood glucose <4.0 mmol/L

Aetiology

Important causes: ^[Ref]

Adrenal insufficiency
Insulinoma
Alcohol intoxication
Critical illness (e.g. sepsis, end-stage liver failure)
Medications
- Certain diabetes medications (insulin and sulfonylurea mainly)
- Beta-blocker toxicity
- Quinine toxicity
Genetic disorders like glycogen storage diseases

Hypoglycaemia most commonly occurs in the context of diabetes, especially in patients treated with insulin or other hypoglycaemia-inducing medications like sulfonylureas

Diagnosis

Clinical Features

Clinical features of hypoglycaemia can be grouped as following: ^[Ref]

Category	Clinical features
Autonomic symptoms (usually seen in <4 mmol/L)	Hunger Tremors / shaking Sweating Irritability Pallor Nausea Paraesthesia Tachycardia / palpitations
Neuroglycopaenic symptoms (usually seen in <3 mmol/L)	Confusion Weakness / fatigue Dizziness Behavioural changes Visual disturbances Loss of consciousness / seizures (in severe cases)

Investigation and Diagnosis

2 main tests are used to diagnose hypoglycaemia:

Finger-prick blood glucose test: a quick bedside tool to measure blood glucose
Serum glucose measurement: more accurate

The Whipple’s triad is used to diagnose true hypoglycaemia:

Hypoglycaemia features (see above)
Documented low serum glucose at the time of symptoms
Relief of symptoms after glucose correction

Management

Blood Glucose ≥4.0 mmol/L

If there are symptoms of hypoglycaemia but blood glucose >4.0 mmol/L → treat with carbohydrate snack or normal meal (if due).

Blood Glucose <4.0 mmol/L

Conscious and Able to Sallow

1st line: oral fast-acting carbohydrate (e.g. glucose tablet, glucose 40% gel, pure fruit juice)

Glucose gel is preferred in those who are not capable and not cooperative (e.g. confused, disoriented, aggressive)
Avoid chocolate and biscuits as they have a lower sugar content, and their high fat content may delay stomach emptying
Repeat up to 3 times (15 min apart)
Once blood glucose >4 mmol/L → provide a long-acting carbohydrate

2nd line (no response to 3 treatment cycles): IM glucagon or IV glucose infusion

Unconscious / Unable to Swallow

1st line (IV access present): IV glucose infusion (100 mL of 20% dextrose or 200 mL of 10% dextrose over 15 min)

If no IV access: glucagon IM (1 mg)
Re-check glucose level after 10 min, and repeat treatment if necessary
Once blood glucose >4 mmol/L → provide a long-acting carbohydrate

Do NOT omit subsequent insulin doses. The insulin regimen should be reviewed.

IV glucose works faster and more reliably than IM glucagon, making it the preferred treatment for severe (e.g., unconscious/fitting patient) hypoglycaemia when IV access is available. Glucagon is also less effective in patients with depleted glycogen stores (i.e., severe liver disease/undernourished patients).

NOTE: The BNF hypoglycaemia treatment summary lists glucagon as the first-line intervention for severe hypoglycaemia (i.e., in unconscious/fitting/very aggressive patients) as it is more practical for non-medical responders (i.e., outside hospital / with no IV access). However, in hospital settings where IV access is readily available, IV glucose is typically preferred (e.g., as per JBDS guidelines).

References

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