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Hyperosmolar Hyperglycaemic State (HHS)

Also known as: HHS · hyperosmolar non-ketotic coma · HONK

A life-threatening emergency of type 2 diabetes — very high glucose, marked hyperosmolality and profound dehydration WITHOUT significant ketosis or acidosis. It develops more slowly than DKA and carries a higher mortality.

Source · Reviewed 2026-08-15 · v1.0— AI-assisted draft — verify against the cited guideline before clinical use.

⚕️ Education only — not medical advice. Verify against the latest official guideline and your local protocol; confirm every drug dose against the cited source before clinical use.

Who gets it

Older people with type 2 diabetes, usually with an intercurrent illness (infection, MI, stroke) or missed medication; sometimes the first presentation of diabetes.

Red flags — escalate / refer

Reduced consciousness, severe dehydration or shock, focal neurology/seizures, or a serious precipitant (sepsis, acute coronary syndrome) → emergency.

Work-up / diagnosis

1Capillary and laboratory glucose, serum osmolality, U&E, and ketones/venous gas to separate HHS (minimal ketones/acidosis) from DKA.
2Search for the precipitant — septic screen, ECG and relevant imaging.

Management — overview

Careful IV fluid replacement is the priority — the deficits are large and must be corrected gradually.
Give insulin cautiously and usually at a lower rate than DKA, often only once fluids are running (fluids alone lower glucose substantially).
Replace potassium as needed, treat the precipitant and give VTE prophylaxis (high thrombosis risk).
Monitor osmolality and avoid too-rapid correction.

In-depthFull dosing & advanced protocol

Drug dosing

IV isotonic fluids (mainstay)

Correct the large water/sodium deficit gradually

Adult dose: Per protocol, guided by osmolality and cardiac/renal reserve
Route: Intravenous

Caution: Avoid over-rapid osmolality shifts (cerebral oedema); watch for fluid overload.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

Low-rate insulin (± potassium)

After fluids; lower rate than DKA

Adult dose: Fixed-rate infusion per protocol once fluids started; replace potassium
Route: Intravenous

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

HHS vs DKA, and slow correction

HHS has high osmolality with only mild ketones/acidosis, unlike DKA.
Fluids do most of the glucose-lowering; insulin is cautious and secondary.
Correct osmolality slowly and give VTE prophylaxis — thrombosis risk is high.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

References

Guidelines change. If something here is out of date, tell us — we keep these current.

🚩 Report outdated / suggest update

More protocols

Type 2 Diabetes MellitusChronic hyperglycaemia from insulin resistance plus relative insulin deficiency — a major driver of cardiovascular, renal, eye and nerve disease.HypothyroidismDeficient thyroid hormone — fatigue, weight gain, cold intolerance, constipation, dry skin and bradycardia. Levothyroxine replacement titrated to TSH.Diabetic Ketoacidosis (DKA)An acute hyperglycaemic emergency of insulin deficiency — hyperglycaemia, ketosis and metabolic acidosis. Fluids, fixed-rate insulin and potassium are the pillars of treatment.

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👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

IV isotonic fluids (mainstay)

Low-rate insulin (± potassium)

📈 HHS vs DKA, and slow correction

📚 References

More protocols

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

IV isotonic fluids (mainstay)

Low-rate insulin (± potassium)

📈 HHS vs DKA, and slow correction

📚 References

More protocols

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

HHS vs DKA, and slow correction

References

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

HHS vs DKA, and slow correction

References