ICU · Endocrine

Hypoglycaemia in the ICU

Also known as Hypoglycaemia · Hypoglycaemic coma · Insulin overdose · Neuroglycopenia · Whipple triad · Sulfonylurea overdose · Octreotide · Insulinoma · Hypoglycaemia-associated autonomic failure · Insulin autoimmunity (Hirata syndrome)

Hypoglycaemia is a frequent and serious adverse effect of antidiabetic therapy; inpatients who develop it have longer stays and increased mortality. In ICU trials moderate hypoglycaemia spans 2.3–3.9 mmol/L (41–70 mg/dL) and severe hypoglycaemia means glucose at or under 2.2 mmol/L (40 mg/dL) — severe episodes carried an adjusted hazard ratio for death of 2.10 in the NICE-SUGAR cohort. Profound hypoglycaemia — typically under 1 mmol/L (18 mg/dL) with a flat EEG — causes neuronal death (hippocampal dentate gyrus and superficial cortex vulnerable; cerebellum and brainstem spared). Causes: insulin or insulin secretagogue treatment (the most common cause), sulfonylurea poisoning (sustained hypoglycaemia refractory to IV dextrose — add octreotide), critical illnesses, hormone deficiencies such as adrenal crisis, non-islet cell tumours, and accidental/surreptitious insulin. Management: check glucose in any unconscious or seizing patient (ICU point-of-care meters read higher than laboratory values, under-detecting hypoglycaemia); oral carbohydrate if conscious; IV dextrose if not (25 g of 50% dextrose is the conventional ampule; 10% dextrose resolves symptoms with fewer adverse events); IM glucagon 1 mg if there is no IV access (intranasal glucagon 3 mg is non-inferior); octreotide 50 µg SC/IV followed by three 50 µg doses every 6 hours for sulfonylurea poisoning; thiamine 200 mg IV three times daily given before any carbohydrate in the malnourished or alcoholic patient; hydrocortisone 100 mg IV bolus then 200 mg/24 h for adrenal crisis. Document Whipple's triad, then take the critical sample (insulin, C-peptide, proinsulin, beta-hydroxybutyrate, oral hypoglycaemic agents, insulin antibodies) to find the cause.

Checked against its sources on 3 Sept 2026