DKA and HHS: when diabetes becomes a medical emergency

The two faces of a diabetes crisis

Diabetes management, most of the time, is a routine of monitoring, medication, and lifestyle. But two emergencies can overturn that: diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS). Both represent a breakdown in the body’s ability to regulate blood glucose and fluid balance — and both require hospital care.

DKA arises when the body has no effective insulin. Without it, cells cannot use glucose, fat is broken down into ketones, and the blood becomes dangerously acidic. HHS is a different process: there is enough residual insulin to prevent ketone formation, but not enough to stop blood glucose from climbing to extreme levels — sometimes above 50 mmol/L — causing profound dehydration and, often, altered consciousness.

Understanding what triggers these crises, recognising the warning signs, and knowing when to call 000 is genuinely life-saving knowledge for anyone living with diabetes.

A. Core clinical — the AU general-practice framework

What distinguishes DKA from HHS

The Australian Diabetes Society and the Joint British Diabetes Societies Inpatient Care Group (JBDS-IP) define DKA as the combination of raised blood glucose (≥11 mmol/L, though it can be lower on SGLT2 inhibitors), significant ketones (capillary β-hydroxybutyrate ≥3 mmol/L), and metabolic acidosis (venous pH below 7.30). HHS, by contrast, features extreme hyperglycaemia (typically above 30–33 mmol/L), hyperosmolality (concentrated blood), minimal ketones, and altered consciousness or severe dehydration — but no significant acidosis.

Mixed presentations exist. Mortality statistics are stark: DKA carries roughly 1–2% mortality overall (higher in older adults and those with late presentation); HHS carries 10–20% mortality, largely because it occurs in frailer, older patients with multiple comorbidities and is often recognised late.

What triggers these crises

The most common trigger for both conditions is infection — urinary tract infection, pneumonia, cellulitis, or dental abscess account for 30–40% of DKA episodes. RACGP data confirms that missed infection is the most common reason DKA is initially misdiagnosed.

Other common triggers include:

• Insulin omission — accidental, financial, or related to eating disorders (in type 1 diabetes, insulin restriction for weight loss is called “diabulimia”)
• New-onset diabetes — approximately 25–30% of type 1 diabetes diagnoses present as DKA
• Medication effects — corticosteroids, atypical antipsychotics, and importantly SGLT2 inhibitors (empagliflozin, dapagliflozin), which can cause euglycaemic DKA with near-normal blood glucose
• Cardiovascular events — myocardial infarction, stroke, and pulmonary embolism
• Physiological stress — surgery, trauma, and severe psychological stress

Recognising DKA in general practice

In type 1 diabetes, DKA typically develops over hours to a day. The warning signs are: nausea and vomiting (present in about 80%), abdominal pain (in about 50% of adults — severe enough to mimic a surgical abdomen), thirst, polyuria, fatigue, and deep sighing respiration (Kussmaul breathing). Breath may smell fruity from acetone.

In type 2 diabetes, DKA usually evolves more slowly but is increasingly seen with SGLT2 inhibitor use, where blood glucose may appear deceptively normal. The TGA has issued specific warnings about euglycaemic DKA on SGLT2 inhibitors and requires cessation at least 72 hours before elective surgery or extended fasting.

Recognising HHS in general practice

HHS develops over days to weeks in older adults with type 2 diabetes. The presenting picture is severe thirst, excessive urination followed by progressive dehydration, worsening lethargy, and finally altered consciousness. About 25% of HHS patients develop focal neurological signs that can mimic stroke. Nursing home residents and elderly people with limited fluid access are at particular risk.

Any elderly person with known or suspected diabetes who becomes confused and appears dehydrated warrants urgent assessment and blood glucose measurement.

The GP’s immediate action

The GP role in suspected DKA or HHS is to recognise and transfer — not to initiate insulin in the clinic. Per JBDS-IP guidance, insulin must not be started in a general practice setting because unsupervised insulin administration can cause fatal hypokalaemia or cerebral oedema.

Immediate GP steps:

1. Call 000 for an ambulance with advanced life support if there is haemodynamic compromise, altered consciousness, or remote location. Otherwise arrange urgent ED transfer.
2. Establish intravenous access if the clinic is equipped; commence 0.9% normal saline 1 L over 1 hour while awaiting transport.
3. Obtain a capillary blood glucose and, if available, capillary ketones (≥3.0 mmol/L is significant).
4. Do a urine dipstick checking glucose, ketones, leucocytes, nitrites, and a pregnancy test in any reproductive-age woman.
5. Perform a 12-lead ECG in adults — hyperkalaemia (peaked T waves, widened QRS) is a life-threatening complication.
6. Document all findings clearly and hand over to ambulance and ED.

B. The SGLT2 inhibitor and euglycaemic DKA issue

Why this is a modern clinical hazard

SGLT2 inhibitors are now widely prescribed in Australia for type 2 diabetes, heart failure with reduced ejection fraction, and chronic kidney disease because of their demonstrated cardiorenal benefits. They lower blood glucose by causing the kidneys to excrete glucose — but this effect simultaneously suppresses insulin secretion and promotes ketone production.

When a patient on an SGLT2 inhibitor is fasting, ill, on a low-carbohydrate diet, or about to have surgery, the risk of euglycaemic DKA rises substantially. The trap is that blood glucose may be only mildly elevated (sometimes below 11 mmol/L) — below the traditional DKA threshold — yet dangerous ketosis is present.

Peters et al. (Diabetes Care 2015) identified this phenomenon, and the TGA’s safety advisory mandates that all patients taking SGLT2 inhibitors receive specific sick-day counselling. The ADA Standards of Care 2025 recommend stopping SGLT2 inhibitors at least 72 hours before elective surgery, colonoscopy preparation, or any period of extended fasting.

Key messages for patients on SGLT2 inhibitors

• Always carry a medical identification and inform any treating clinician that you are on an SGLT2 inhibitor before surgery or procedures.
• If you feel unwell, vomit, or are not eating, stop the SGLT2 inhibitor immediately and contact your GP or go to hospital.
• If blood glucose seems normal but you feel unwell, check ketones — the normal blood sugar does not rule out DKA on these medications.

C. Hospital treatment — what patients and families should know

DKA protocol in hospital

Hospitals follow structured DKA protocols based on JBDS-IP 2023 and the eTG (Therapeutic Guidelines). The key steps are:

Fluid resuscitation — intravenous 0.9% saline is given urgently to correct dehydration, typically 1 L over the first hour then more slowly over subsequent hours.

Potassium replacement — blood potassium is measured urgently. Total body potassium is depleted in DKA even when blood levels appear normal, because acidosis causes potassium to shift out of cells. When insulin is given, potassium shifts back into cells and blood levels fall rapidly. Insulin is not started until potassium is ≥3.5 mmol/L, and potassium is added to each bag of intravenous fluid throughout treatment.

Fixed-rate intravenous insulin — a continuous low-dose insulin infusion (0.1 units/kg/hour) is started to clear ketones. The target is clearance of ketones (β-hydroxybutyrate below 0.6 mmol/L) and normalisation of pH — not simply bringing blood sugar down. Long-acting basal insulin is usually continued throughout.

Trigger search — the team investigates what caused the crisis: blood cultures, imaging, urine tests, ECG, inflammatory markers.

Transition off insulin infusion — once ketones are cleared and the patient is eating, subcutaneous insulin is restarted with a one-hour overlap period to prevent rebound DKA.

HHS protocol in hospital

HHS requires slower, more cautious fluid replacement than DKA. The goal is to gently lower blood glucose and blood osmolality over 24–48 hours to prevent cerebral oedema or osmotic demyelination. Insulin is used only if ketones are also present (mixed HHS-DKA) or if blood glucose is not responding to fluids alone. Thromboprophylaxis is standard because HHS carries a very high clotting risk.

D. Australian operations

National Diabetes Services Scheme (NDSS)

The NDSS is Australia’s registration-based diabetes support program providing subsidised access to glucose monitoring consumables, ketone strips, CGM sensors (for type 1 diabetes since July 2022), insulin syringes, and pen needles. NDSS registration is free and is arranged through the GP or diabetes educator. Every person with type 1 diabetes should be registered and should have subsidised ketone strips — checking ketones promptly during illness is the cornerstone of DKA prevention.

MBS items for diabetes follow-up after DKA or HHS

Post-discharge GP care attracts standard consultation items (MBS items 23, 36, or 44). The GP Chronic Condition Management Plan (GPCCMP, MBS items 965/967) enables referral to a credentialled diabetes educator (MBS item 10951), dietitian (10954), exercise physiologist (10953), podiatrist (10962), and psychology (MBS items 80000–80020 under Mental Health Treatment Plan items 2715/2717). GPCCMP replaced the former Chronic Disease Management Plans on 1 July 2025.

PBS — insulin and related medications

All insulin formulations — rapid-acting, short-acting, intermediate, and long-acting analogues — are PBS Authority Required Streamlined for diabetes mellitus. SGLT2 inhibitors (empagliflozin, dapagliflozin, ertugliflozin) are PBS Authority Required Streamlined for type 2 diabetes with cardiovascular, renal, or heart failure indications; they are not PBS-approved for type 1 diabetes in Australia. Glucagon emergency kits (GlucaGen intramuscular, Baqsimi intranasal) are PBS-listed under Authority Required Streamlined for insulin-treated patients.

Sick-day management and patient education

Diabetes Australia and the Australian Diabetes Society publish sick-day management toolkits. The GP should ensure every patient with type 1 diabetes has a written sick-day plan — the three S rule (Sugar, Stay hydrated, Stay on insulin) — documented in their care plan and rehearsed with their diabetes educator.

Driving and Austroads

Austroads national standards apply to all insulin-treated people. Blood glucose must be ≥5 mmol/L before driving, and rechecked every 2 hours on long trips with accessible glucose. A severe hypoglycaemic or DKA event may require notification to the state licensing authority for commercial licence holders. The GP should document advice given. See the Austroads Assessing Fitness to Drive 2022 guidance.

MedicAlert

MedicAlert Foundation Australia bracelets and digital IDs alert emergency responders to diabetes, insulin use, and specific medication risks (such as SGLT2 inhibitor DKA risk). Counsel all patients with type 1 diabetes and high-risk type 2 patients to register.

E. Special populations

Children and adolescents

Approximately 30% of new type 1 diabetes diagnoses in children present as DKA. Paediatric DKA carries an additional specific risk: cerebral oedema, which occurs in about 1% of paediatric DKA cases and carries a mortality of up to 25% of those affected. The risk factors for cerebral oedema are severity of acidosis and hypocapnia at presentation — not, contrary to older thinking, the rate of fluid administration (confirmed by the PECARN PrEDICT trial, NEJM 2018). Any child with deteriorating consciousness, headache, vomiting, or Cushing reflex (rising BP and slowing heart rate) during DKA treatment requires urgent senior review and probable mannitol or hypertonic saline.

Paediatric diabetes is managed through specialist paediatric endocrine services. The GP’s role is to recognise DKA in a child presenting with new symptoms — polyuria, polydipsia, weight loss, vomiting — and transfer immediately.

Eating disorders and “diabulimia”

In young women with type 1 diabetes, deliberate restriction of insulin to lose weight is termed “diabulimia.” It is significantly underdiagnosed and drives repeated DKA episodes. Any patient with recurrent DKA (two or more episodes per year), persistent elevated HbA1c despite apparent compliance, or expressed anxiety around insulin should be screened with a diabetes-specific eating disorder tool and referred to a specialist team combining endocrinology and eating disorder psychology. A Mental Health Treatment Plan (MBS 2715/2717) supports psychology referral.

Older adults

Older adults with type 2 diabetes are the primary HHS population. They often have reduced thirst sensation, limited mobility or access to fluids, multiple comorbidities, and polypharmacy that increases metabolic vulnerability. Annual influenza vaccination, pneumococcal vaccination (Prevenar 20), COVID-19 booster, and RSV vaccine (for those ≥60) reduce the infection triggers that most commonly precipitate HHS. The 75+ Health Assessment (MBS item 705) provides an annual structured opportunity to review diabetes management and medication burden.

Aboriginal and Torres Strait Islander peoples

Type 2 diabetes affects Aboriginal and Torres Strait Islander peoples at 3–4 times the rate of non-Indigenous Australians, with earlier onset and higher rates of complications. The Aboriginal and Torres Strait Islander Health Assessment (MBS item 715) provides an annual structured review. Care should be culturally safe and, where possible, delivered through Aboriginal Community Controlled Health Organisations (ACCHOs). Closing the Gap PBS co-payment support reduces medication cost barriers.

When to escalate

Call 000 or arrange immediate ED transfer for:

• Any suspected DKA (vomiting, abdominal pain, Kussmaul breathing in a person with diabetes) or capillary ketones ≥3.0 mmol/L
• Any elderly person with diabetes with altered consciousness and suspected HHS
• Any child with new diabetes symptoms (polyuria, polydipsia, weight loss, vomiting)
• Haemodynamic instability — heart rate ≥120, systolic BP ≤90, or syncope
• Confirmed or suspected pregnancy with ketosis

Refer to endocrinology for: recurrent DKA (≥2 episodes per year), suspected eating disorder with insulin omission, SGLT2 inhibitor-related euglycaemic DKA decisions in type 2 diabetes, and complex insulin regimen optimisation.

What this article is and is not

This is general health information drawn from current Australian general practice and specialist guidelines — the Australian Diabetes Society, Therapeutic Guidelines, AMH, TGA, NDSS, JBDS-IP, and ADA Standards of Care — and is intended to help patients and families understand DKA and HHS. It is not personal medical advice and does not create a doctor–patient relationship. Decisions about specific treatment, insulin regimens, and medication management are made with your own GP and treating clinicians.

For diabetes emergencies: call 000.

For peer support and education: NDSS, Diabetes Australia, HealthDirect — Diabetic ketoacidosis. For crisis support: Lifeline 13 11 14, Beyond Blue 1300 22 4636.

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Sources cited

1. Australian Diabetes Society — Inpatient management of DKA and HHS
2. Therapeutic Guidelines (eTG) — Endocrinology: DKA and HHS
3. TGA — SGLT2 inhibitors and risk of diabetic ketoacidosis
4. RACGP — Diabetic ketoacidosis: a missed diagnosis (AJGP)
5. Australian Medicines Handbook — insulin and SGLT2 inhibitor monographs
6. JBDS-IP — Management of DKA in Adults 2023
7. JBDS-IP — Management of HHS in Adults 2022
8. ADA Standards of Care in Diabetes 2025 — Diabetes Crises
9. NDSS — National Diabetes Services Scheme
10. Diabetes Australia — Sick day management
11. Peters et al. — Euglycaemic DKA with SGLT2 inhibitors (Diabetes Care 2015)
12. Austroads — Assessing Fitness to Drive 2022
13. MedicAlert Foundation Australia
14. HealthDirect — Diabetic ketoacidosis