Poisoning from - antidiabetic medicines

Description

Overdose of sulfonylureas (glipizide, gliclazide) or insulin -> prolonged, severe hypoglycaemia
Metformin overdose -> rarely hypoglycaemic alone; risk is metformin-associated lactic acidosis (MALA), especially with renal impairment
SGLT2 inhibitors -> euglycaemic DKA risk (not classic overdose toxicity)

Deliberate self-poisoning, accidental paediatric ingestion of a relative's sulfonylurea (even one tablet can cause prolonged hypoglycaemia in a child)
Insulin overdose - deliberate self-harm or dosing error

Sulfonylureas: bind SUR1 on pancreatic beta-cells -> close K-ATP channels -> insulin release independent of glucose level -> prolonged hypoglycaemia (half-life dependent, can last >24h)
Insulin: duration depends on formulation - long-acting analogues cause prolonged hypoglycaemia over days
Metformin: inhibits mitochondrial complex I -> impaired hepatic gluconeogenesis + lactate clearance -> lactic acidosis in overdose or accumulation (renal impairment, AKI)

Capillary/lab glucose; serial monitoring mandatory even after initial correction - sulfonylurea hypoglycaemia recurs
VBG/lactate + renal function if metformin involved - lactate often markedly high (>5-10 mmol/L) in MALA

Hypoglycaemia (sulfonylurea/insulin)

IV dextrose for immediate correction, then:
Octreotide - suppresses further insulin release from beta-cells in sulfonylurea overdose (dextrose alone can paradoxically worsen it by re-stimulating insulin release)
Admit for prolonged glucose monitoring (24h+ for sulfonylureas; days for long-acting insulin analogues)
Feed the patient - a meal reduces recurrent hypoglycaemia

MALA

Supportive, correct acidosis, early renal replacement therapy (haemodialysis) for severe acidosis, high lactate, or renal failure - clears both metformin and lactate

Prolonged fasting, renal impairment, alcohol - all potentiate sulfonylurea hypoglycaemia and MALA risk
Missed recurrent hypoglycaemia -> neuroglycopenic seizure, coma, permanent injury

Sulfonylurea hypoglycaemia can recur for 24-72h depending on agent and renal function - premature discharge is the main preventable harm
MALA mortality substantial if unrecognised; good outcome with early dialysis

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