Hyperosmolar Hyperglycaemic State Insulin Therapy

Hyperosmolar hyperglycaemic state is severe hyperglycaemia with marked dehydration and little or no ketosis, mostly in older adults with type 2 diabetes. It is diagnosed by glucose of 30 mmol/L or more, effective osmolality of 320 mOsm/kg or more, venous pH over 7.3, bicarbonate over 15 mmol/L, and ketones under 3.0 mmol/L. Mortality is high. Fluid replacement is the first treatment, and insulin is delayed.

Calculated osmolality. 2 times sodium, plus glucose, plus urea, all in mmol/L.

Precipitants. Infection, myocardial infarction, stroke, steroids, antipsychotics, thiazide diuretics, and new-onset diabetes.

Rate limits. Glucose should fall by no more than 5 mmol/L/hour, osmolality by 3 to 8 mOsm/kg/hour, and sodium by no more than 10 mmol/L in 24 hours, to avoid cerebral oedema and osmotic demyelination.

Fluids. 0.9% sodium chloride is the first fluid; if sodium rises over 150 mmol/L with adequate volume, move to 0.45% sodium chloride.

Insulin. Not started with fluid resuscitation in most patients. Start only if glucose is not falling by at least 5 mmol/L/hour with fluids, or if ketones are over 1.0 mmol/L.

Anticoagulation. Prophylactic low molecular weight heparin for all patients, because thrombosis risk is high.

Fluids. Give 0.9% sodium chloride 1 litre over the first hour (500 mL over 10 to 15 minutes if systolic blood pressure is under 90 mmHg). Replace about half of the estimated deficit (often 100 to 220 mL/kg in total) over the first 12 hours and the rest over the next 12 hours. Aim for about 3 to 6 litres in 24 hours, with smaller volumes and slower rates in heart or kidney failure.

Insulin. When indicated, start fixed-rate insulin 0.05 units/kg/hour. If glucose falls under 14 mmol/L, add 5% or 10% glucose 125 mL/hour and keep the insulin running to clear ketones. Stop insulin when glucose is 10 to 15 mmol/L with osmolality falling and no ketosis, and move to a variable rate if needed.

Potassium. Give potassium only after urine output is confirmed: none if over 5.5 mmol/L, 40 mmol in each litre of fluid if 3.5 to 5.5 mmol/L, and replace first if under 3.5 mmol/L.

Thromboprophylaxis. Enoxaparin 40 mg subcutaneously once daily, or 1 mg/kg once daily in high risk; reduce for kidney impairment.

Special groups. - Older adults: use cautious fluid rates and assess cardiac function. - Kidney impairment: dialysis is rarely needed; adjust fluids by urine output. - Children and young people: hyperosmolar presentations are uncommon; treat in a specialist unit. - Pregnancy: rare; manage in critical care.

Monitoring. Glucose hourly, sodium and osmolality every 2 hours initially, potassium every 2 hours, and fluid balance hourly. Examine feet and pressure areas daily, because pressure injuries and foot ulcers are common.

Complications. Hypokalaemia, hypoglycaemia, thrombosis, cerebral oedema, pulmonary oedema, rhabdomyolysis, and acute kidney injury.

Stopping. Move to subcutaneous insulin when the patient is eating, glucose is under 15 mmol/L, and osmolality is under 300 mOsm/kg.

Referral and escalation. Escalate to critical care for osmolality over 350 mOsm/kg, sodium over 160 mmol/L, pH under 7.1, systolic blood pressure under 90 mmHg, oliguria, Glasgow Coma Scale under 12, or serious comorbidity.