Hyperosmolar Hyperglycaemic State Management
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Direct answer
Unlike diabetic ketoacidosis, the hyperosmolar hyperglycaemic state develops over days to weeks in an older type 2 diabetes patient: profound dehydration, glucose above 600 mg/dL, effective osmolality above 320 mOsm/kg, and — by definition — preserved insulin action, so pH stays above 7.30, bicarbonate at 18 mmol/L or more, and ketosis remains trivial. Management is measured where DKA is urgent: isotonic saline first at 15–20 mL/kg in the initial hour, then osmolality-guided replacement of a 6–10 litre water deficit over one to two days, with insulin at 0.1 units/kg/hour playing a supporting role. Glucose should fall no faster than 50–75 mg/dL/hour and osmolality no more than about 3 mOsm/kg/hour, because abrupt shifts risk osmotic brain injury. Low-molecular-weight heparin thromboprophylaxis is mandatory, and mortality — chiefly in older patients with precipitating illness — exceeds that of DKA several-fold.
What you must remember
- Diagnostic numbers: glucose over 600 mg/dL (often 800–1,000), effective osmolality (2× sodium + glucose/18) over 320 mOsm/kg, pH above 7.30, bicarbonate at least 18, small ketones only.
- Why no ketosis: residual insulin action suppresses lipolysis — the single most-asked physiological question; these patients are insulin-resistant but not insulin-deficient in the DKA sense.
- Corrected sodium matters: add roughly 1.6 mmol/L (some use 2.4) per 100 mg/dL glucose above 100 — a "normal" sodium at glucose 900 means severe hypertonic dehydration needing free-water replacement.
- Fluid strategy: 0.9 per cent saline 15–20 mL/kg in the first hour; then, once volume-restored, 0.45 per cent saline guided by corrected sodium and osmolality; replace the deficit over 24–48 hours plus ongoing losses.
- Insulin humility: 0.1 units/kg/hour after initial potassium check; requirements are often lower than DKA, and insulin sensitivity improves dramatically as osmolality normalises — anticipate the drop.
- Potassium: total-body deficits rival or exceed DKA (4–6 mmol/kg); replace once urine output and levels allow, as with DKA rules.
- Thromboprophylaxis: the hyperosmolar, hyperviscous state carries high arterial and venous thrombotic risk — prophylactic LMWH for the admission unless contraindicated.
- Neurology: focal deficits and seizures flow from hyperosmolality itself and reverse with treatment; over-rapid sodium correction adds osmotic demyelination risk in these chronically adapted brains.
- Precipitants: infection (pneumonia, urinary sepsis), myocardial infarction, stroke, and diabetogenic drugs — thiazides, steroids, sympathomimetics; silent myocardial infarction is a classic hidden trigger in the elderly.
Resuscitation at ward pace
A 68-year-old man, drowsy but rousable, brought by family after a week of polyuria and declining intake; glucose 940 mg/dL, sodium 158 mmol/L, urea high, effective osmolality 358. First hour: 1–1.5 L of 0.9 per cent saline to restore perfusion — the initial salt load lowers glucose by renal clearance alone. Hour by hour thereafter: corrected sodium is calculated every few hours; with persistent hypernatraemia the fluid becomes 0.45 per cent saline via a pump, targeting an osmolality decline of roughly 3 mOsm/kg/hour and sodium correction within the safe daily band. Insulin 6 units/hour begins after potassium is confirmed safe; by hour six glucose has fallen to about 600 — on track — and when it reaches 250–300, dextrose is added so insulin can continue until osmolality normalises. LMWH is given on arrival. He develops no ketosis, needs no bicarbonate, and by day two is drinking; the discharge workup includes a silent ischaemia screen, a review of his thiazide, and structured diabetes education — because in Indian practice HHS clusters in elderly patients living alone whose oral hypoglycaemics ran out silently. The whole craft lies in patience: the glucose of 940 fell over two days, and correcting it in six hours is not rescue but injury.
What candidates miss
The first miss is definitional — quoting ketone-positive, acidotic numbers for HHS; a single ketone-positive, acidotic patient is DKA (or a mixed state), and the distinction changes fluid priorities. The second is fluid arithmetic: candidates fear the sodium but forget that the free-water deficit, often 8–10 litres, is the true target. The third is prevention of the second complication — thrombosis; examiners specifically ask "what else is given on day one besides fluids and insulin" expecting LMWH. Finally, rhabdomyolysis and acute kidney injury complicate severe cases, so creatine kinase and urine output belong in the monitoring set — a point that distinguishes a specialist answer from a textbook recital.
Frequently asked questions
What biochemical criteria separate HHS from DKA?
Glucose above 600 mg/dL with effective osmolality above 320 mOsm/kg, but pH above 7.30, bicarbonate at least 18 mmol/L, and only minimal ketones — residual insulin prevents lipolysis and ketogenesis.
Why is correction slower in HHS than in DKA?
The brain has adapted over days to weeks of hyperosmolality; rapid falls in osmolality and sodium cause osmotic cerebral oedema and demyelination, so deficits are replaced over 24–48 hours.
When is insulin started and at what dose?
After initial fluid resuscitation and a potassium check, at 0.1 units/kg/hour — often lower maintenance needs than DKA, and it is reduced once osmolality and glucose begin falling steadily.
Which prophylaxis is routine in HHS?
Low-molecular-weight heparin thromboprophylaxis, since hyperosmolality and dehydration markedly raise venous and arterial thrombotic risk.
How fast should glucose fall in HHS?
Around 50–75 mg/dL/hour, achieved mainly by fluids; when glucose reaches 250–300 mg/dL, dextrose is added so insulin can continue until osmolality normalises.