Hypoglycaemia

Introduction
In health, plasma glucose is tightly regulated between 3.6-5.8mmol/l.
Hypoglycaemia is the most common endocrine emergency and is generally defined by a lab plasma blood glucose of < 3.5mmol/l.
It can mimic many other neurological presentations such as acute confusion, coma, seizures, alcohol intoxication or withdrawal and stroke and can vary in presentation in diabetic and non-diabetic patients.
In insulin-dependent diabetic patients, hypoglycaemia accounts for 2.6% of mortality and thus early recognition and management is crucial.

Presentation
Patients who are hypoglycaemic generally present with features of either sympathetic overactivity or of neuroglycopenia.
Signs and symptoms of sympathetic overactivity (glucose<3.6mmol/l) include tachycardia, palpitations, anxiety, sweating, hunger, tremor and cold extremities.
Features of neuroglycopenia (glucose<2.6mmol/l) are irritability, confusion, slurred speech, focal neurological deficits and coma.

At plasma glucose levels below 3mmol/l cognitive function is likely to be impaired. Coma usually occurs with a serum glucose of <1.5mmol/l.

Patients with well-controlled diabetes mellitus experience more hypoglycaemic episodes generally and may become desensitised to sympathetic activation over time. This results in a loss of the ‘warning’ symptoms of a hypoglycaemic episode for these patients. Patients who have developed diabetes following total pancreatectomy also have more frequent episodes of hypoglycaemia due to a lack of glucagon producing α cells as well as β islet cells.

Symptoms of sympathetic activation are also dampened by β-blockade.

Patients with poorly controlled diabetes may develop sympathetic signs early and avoid this by running a high blood glucose, thus this patient group may become symptomatic of hypoglycaemia when their blood glucose is normal or even high.

Causes
In diabetic patients the commonest cause of hypoglycaemia is an imbalance of administered and required insulin or oral hypoglycaemic agent.

Other causes include one or a combination of:

Drugs

• • Alcohol
  • Insulin (consider self-harm with insulin overdose)
  • Sulphonylureas
  • Salicylates
  • Others – β blockers, Pentamidine, Quinine, Disopyramide
  • Prescription errors

Behavioural

• • Insufficient or delayed food intake
  • Unforeseen or excessive exercise (remember intercourse!)

Organ dysfunction

• • Addison’s disease
  • Hepatic failure
  • Post-gastric surgery

Tumours

• • Non-pancreatic tumours
  • Islet cell tumours (Insulinoma)
  • Retroperitoneal sarcoma

Infections

• • Malaria
  • Sepsis

Investigation

• • Blood glucose – BM and confirm with lab formal glucose but give treatment without waiting for the lab result if BM < 3.5
  • If on no treatment for diabetes then send blood for paired glucose and insulin levels
    • U&E’s – particular attention to K+ and renal function

Treatment

Guidance on Hypoglycaemia in Hospital

ABCDE

• • 1st line treatment – Oral glucose (100ml Lucozade, 3-4 Dextrosol sweets or GlucoGel) and complex carbohydrate to prevent recurrence. GlucoGel can be rubbed into buccal mucosa.
  • If unable to administer orally give Glucagon 1mg intramuscularly, subcutaneously or intravenously followed by glucose orally. Glucagon not suitable for treatment of hypoglycaemia due to sulphonylurea drugs, hepatic failure or chronic alcohol abuse (low glycogen mobilization states).
  • If no response or still unconscious – intravenous glucose 25-50ml of 50%(or 50mls of 20%, or 100mls of 10% as immediately available).  Solutions containing high percentages of glucose are hypertonic and should ideally be injected into a large vein and followed by a 0.9% saline flush to decrease the risk of thrombophlebitis.
  • If no response; consider differential diagnoses and discuss with your immediate senior and consider need for escalation to HDU/ICU care. Persisting altered conscious level suggests the likelihood of another pathology (i.e. cerebrovascular event or progression on to cerebral oedema). Aim to maintain plasma glucose between 7-11mmol/l and contact senior member of the medical/ICU on call team for advice.
  • Prolonged hypoglycaemia can cause cerebral oedema; consider intravenous mannitol (200mls 20% over 20 minutes) or dexamethasone (10mg intravenously stat then 4mg qds).  If this is the case, then ICU need to be involved.
  • Continue until clinical improvement and BM greater than 4. 90% of patients fully recover in 20mins.
  • Establish the cause and prevent recurrence. This may involve advising many small high-starch meals if hypoglycaemic episodes are often or rationalizing insulin therapy in diabetics.
  • Glucose infusions may be required in patients where the cause is overdose for 24hours or longer.
  • All patients with hypoglycaemia requiring 3^rd party intervention should be seen by the diabetic specialist nurse before discharge.
  • N.B. Glucose infusions may be required for hypoglycaemia due to sulphoylureas.