FRCEM SBA Revision: DKA & HHS Management & Guidelines Explained

Diabetic emergencies appear in 4–6 FRCEM SBA questions, testing your ability to recognise presentations, interpret biochemistry, and manage life-threatening metabolic crises correctly.

The challenge isn't memorising every detail of DKA and HHS management — it's understanding the key differences between them, knowing when to give insulin versus fluids first, and recognising complications that appear in exam scenarios.

This guide explains DKA and HHS management following the latest UK guidelines — JBDS 02 (DKA, revised March 2023) and JBDS 06 (HHS, February 2022) — focusing on what FRCEM actually tests.

DKA vs HHS: The Critical Differences

Understanding the distinction between diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS) is fundamental.

Diabetic Ketoacidosis (DKA)

Diagnostic criteria (all three required):

• Blood glucose >11 mmol/L (or known diabetes)

• Ketones >3 mmol/L (blood) OR ++ on urine dipstick

• Venous pH <7.3 and/or bicarbonate <15 mmol/L

Typical patient: Type 1 diabetic, younger, acute presentation

Pathophysiology: Absolute insulin deficiency → unrestrained ketone production → metabolic acidosis

Presentation: Rapid onset (hours), severe metabolic derangement, Kussmaul breathing, ketotic ("pear-drop") breath

New for FRCEM 2023+: SGLT-2 inhibitors (e.g., empagliflozin, dapagliflozin) can cause euglycaemic DKA — DKA with a near-normal blood glucose (can be <11 mmol/L). Suspect this if a patient on an SGLT-2 inhibitor presents with acidosis and ketonaemia but glucose appears only mildly elevated. Treatment is identical to standard DKA. Stop the SGLT-2 inhibitor immediately.

Also new: Ketosis-prone type 2 diabetes — most common in people of African-Caribbean or Hispanic descent. Presents like DKA but insulin can often be stopped soon after resolution once the precipitant is treated.

Hyperosmolar Hyperglycaemic State (HHS)

Diagnostic criteria (JBDS 06, 2022):

• Marked hyperglycaemia ≥30 mmol/L

• Osmolality ≥320 mOsm/kg

• No significant ketosis (blood ketones ≤3.0 mmol/L)

• No significant acidosis (pH >7.3, bicarbonate ≥15 mmol/L)

Osmolality formula: (2 × Na⁺) + glucose + urea

Typical patient: Type 2 diabetic, older, gradual onset over days — but increasingly seen in younger adults and children

Pathophysiology: Relative insulin deficiency → severe hyperglycaemia → profound osmotic dehydration without ketosis

Presentation: Insidious onset (days), profound dehydration, altered consciousness, osmolality often >350 mOsm/kg in severe cases

FRCEM testing: Questions present biochemistry results and ask which diagnosis fits, or test whether you recognise HHS requires much slower correction than DKA over 24–72 hours.

DKA Management Protocol (JBDS 02, March 2023)

Initial Assessment and Resuscitation

Immediate actions (0–60 minutes):

1. Secure airway if GCS <8 or airway at risk

2. High-flow oxygen if hypoxic

3. IV access — large-bore cannula

4. Bloods: VBG, capillary and laboratory glucose, U&E, FBC, blood cultures

5. ECG (check for hyperkalaemia — peaked T-waves, wide QRS)

6. MSU and CXR

7. Commence continuous cardiac monitoring if required

Identify precipitant: Infection (~40%), missed insulin (~25%), new diagnosis (~15%), other

Fluid Resuscitation

First priority in DKA is fluids, not insulin.

If systolic BP <90 mmHg (shocked patient):

• Give 500 ml 0.9% sodium chloride over 10–15 minutes

• If SBP remains <90 mmHg, repeat while awaiting senior input (most require 500–1000 ml rapidly)

• Consider ITU/critical care involvement early

• Once SBP ≥90 mmHg, continue with the standard protocol below

If systolic BP ≥90 mmHg on admission:

Approximately 6 litres over 24 hours in most adults. Reassess regularly — use clinical judgement in elderly, cardiac, or renal patients.

FRCEM angle: Aggressive fluid resuscitation must come before insulin. Starting insulin without adequate volume replacement risks cardiovascular collapse.

Insulin Therapy (⚠️ Updated 2021/2023 — Key Change)

Fixed-rate IV insulin infusion (FRIII):

Initial dose: 0.1 units/kg/hour

⭐ NEW: When glucose falls to ≤14 mmol/L — DE-ESCALATE INSULIN to 0.05 units/kg/hour

This is a critical change from older guidelines. The 2021/2023 JBDS update recommends reducing the FRIII rate from 0.1 to 0.05 units/kg/hour once blood glucose drops to ≤14 mmol/L, to reduce the risk of hypoglycaemia and hypokalaemia. Add 10% glucose alongside this (see below).

Example: 70 kg patient = 7 units/hour initially → reduce to 3.5 units/hour when glucose ≤14 mmol/L

Preparation: 50 units human soluble insulin (Actrapid® or Humulin S®) in 50 ml 0.9% saline (= 1 unit/ml)

Start insulin: Only after the initial fluid bolus has been given

Do NOT stop long-acting insulin: If the patient normally takes a long-acting insulin analogue (glargine/Lantus, detemir/Levemir, degludec/Tresiba), continue it at the usual dose and time. This reduces rebound hyperglycaemia when IV insulin is stopped.

FRCEM testing will cover:

• Initial insulin dose (0.1 units/kg/hour)

• Dose reduction at glucose ≤14 mmol/L (0.05 units/kg/hour) — this is a common exam catch

• Timing: start after fluid bolus, not before

• Whether to stop long-acting insulin (no — continue it)

Potassium Replacement

Critical concept: Insulin drives potassium into cells, causing hypokalaemia. This is the most common cause of death in DKA if not managed.

Replacement protocol:

Monitoring: Check venous bicarbonate and potassium at 60 minutes, 2 hours, then 2-hourly.

FRCEM angle: Questions often present a normal or mildly elevated potassium (e.g., 5.2 mmol/L) and test whether you recognise that replacement will be needed as treatment proceeds.

Monitoring Targets

Hourly:

• Capillary blood glucose

• Capillary ketones (blood ketone measurement is the preferred monitoring method per JBDS)

• If blood ketone measurement unavailable, use venous pH + bicarbonate

Target rates of correction:

• Glucose: fall of 3 mmol/L per hour

• Ketones: fall of 0.5 mmol/L per hour

• Bicarbonate: rise of 3 mmol/L per hour

⭐ When glucose ≤14 mmol/L:

• Reduce FRIII to 0.05 units/kg/hour (see above)

• Add 10% glucose at 125 ml/hour alongside the ongoing saline

• Do NOT stop insulin — ketone clearance requires continued insulin

FRCEM testing: A question presents glucose 12 mmol/L with ketones still 2.5 mmol/L. The correct answer is: reduce insulin to 0.05 units/kg/hour AND add 10% dextrose. Do not stop insulin.

HHS Management Protocol (JBDS 06, February 2022)

The 2022 updated JBDS HHS guidelines introduced a structured 5-phase care pathway (0–60 min, 1–6 hr, 6–12 hr, 12–24 hr, 24–72 hr).

Key principle: Slower, gentler correction than DKA, aiming to replace all fluid losses over 24–72 hours, not 24 hours.

Why Slower Correction Matters

Rapid correction risks neurological complications including cerebral oedema and osmotic demyelination syndrome (central pontine myelinolysis).

Target osmolality fall: 3–8 mOsm/kg/hour (no faster)

Target blood glucose in first 24 hours: 10–15 mmol/L (not normoglycaemia)

Fluid Resuscitation in HHS

Use 0.9% sodium chloride as the principal fluid. Fluid losses in HHS are estimated at 100–220 ml/kg — much greater than DKA — but replacement must be gradual.

Initial fluid regime:

• 1 litre 0.9% NaCl over 1 hour

• 1 litre 0.9% NaCl + KCl over 2 hours

• 1 litre 0.9% NaCl + KCl over 2 hours

• 1 litre 0.9% NaCl + KCl over 4 hours

• Then reassess osmolality, glucose, and clinical status

Important: An initial rise in sodium is expected and is not itself an indication for hypotonic fluids. Only consider 0.45% saline if osmolality is not falling appropriately despite adequate 0.9% NaCl or sodium is rising significantly.

Caution in elderly patients — increased risk of fluid overload; reassess frequently.

Insulin in HHS (⚠️ Important Difference from DKA)

Withhold insulin initially. Fluid replacement alone will cause blood glucose to fall in HHS.

Start FRIII only if:

• Blood glucose is no longer falling with IV fluids alone, OR

• There is ketonaemia (blood ketones rising — if ketones >3 mmol/L, use DKA protocol)

If both DKA and HHS features are present (mixed picture): If ketones >3 mmol/L, default to the DKA protocol; seek early specialist input.

Dose when insulin is indicated: 0.05 units/kg/hour (half the initial DKA rate)

Add 5% or 10% glucose once blood glucose <14 mmol/L (same principle as DKA).

FRCEM testing: Questions on HHS test whether you withhold insulin initially (not first-line unlike DKA) and know the lower dose when insulin is eventually needed.

Thromboprophylaxis in HHS

Essential — give treatment-dose LMWH:

• Enoxaparin 1 mg/kg BD (treatment dose, not just prophylaxis)

• HHS carries very high VTE risk due to hyperosmolality, immobility, and dehydration

The 2022 guidelines also emphasise monitoring for and preventing:

• Foot ulceration (check feet daily)

• Fluid overload

• Hypokalaemia and hypoglycaemia

FRCEM angle: Treatment-dose anticoagulation (not just prophylactic dose) is a key differentiator between HHS and DKA management.

HHS Resolution Criteria (JBDS 06, 2022)

HHS is resolved when all four are met:

• Osmolality <300 mOsm/kg

• Hypovolaemia corrected (urine output ≥0.5 ml/kg/hour)

• Cognitive status returned to pre-morbid baseline

• Blood glucose <15 mmol/L

Note: HHS resolution criteria differ from DKA. HHS resolution is not defined by pH or ketones — it is defined by osmolality correction and clinical recovery.

DKA Complications

Hypokalaemia

Most common cause of death in DKA. Insulin drives K⁺ intracellularly; treatment without adequate replacement worsens this. Start replacement early as per the protocol above.

Cerebral Oedema

Rare but life-threatening, primarily in children and adolescents. Risk factors include age <18, new diagnosis, severe dehydration, and overly rapid fluid or glucose correction.

Signs: Headache, irritability, altered consciousness, Cushing's response (bradycardia + rising BP), papilloedema

Management:

• Reduce IV fluid rate immediately

• IV mannitol 0.5–1 g/kg, or hypertonic (2.7%) saline

• Urgent ICU/PICU referral

Hypoglycaemia

Now recognised as a significant complication of DKA treatment in the 2021/2023 JBDS update. The recommendation to reduce FRIII to 0.05 units/kg/hour when glucose ≤14 mmol/L, combined with timely 10% glucose addition, is specifically designed to address this.

Aspiration Pneumonia

Reduced consciousness + vomiting = aspiration risk. Insert NG tube if vomiting and patient not fully alert; keep NBM until safe.

When to Escalate (DKA)

Involve ICU/HDU if any of the following:

• pH <7.1 despite treatment

• Potassium <3.5 mmol/L despite replacement

• GCS <12

• Oxygen saturation <92%

• Systolic BP <90 mmHg

• Creatinine >200 micromol/L

• Pregnant patient

DKA Resolution Criteria

DKA is resolved when all three are met:

• pH >7.3

• Bicarbonate >15 mmol/L

• Blood ketones <0.6 mmol/L

NOT glucose normalisation — the patient may still have elevated glucose but have resolved acidosis and ketosis.

Transition to Subcutaneous Insulin

1. Give the patient's usual subcutaneous insulin (or initiate insulin if new diagnosis)

2. Wait 30–60 minutes after the subcutaneous dose

3. Then stop the FRIII

This overlap prevents rebound ketosis. Never abruptly stop IV insulin without giving subcutaneous first.

Common FRCEM DKA/HHS Mistakes

Mistake 1: Starting insulin before adequate fluid resuscitation Fluids first in DKA. Insulin without volume replacement risks cardiovascular collapse.

Mistake 2: Not reducing insulin when glucose reaches ≤14 mmol/L Current JBDS 2023 guidance: reduce FRIII to 0.05 units/kg/hour at this point. Add 10% glucose. Do not continue at 0.1 units/kg/hour — this increases hypoglycaemia and hypokalaemia risk.

Mistake 3: Stopping insulin when glucose normalises Continue insulin (at reduced rate) for ketone clearance; add dextrose to prevent hypoglycaemia.

Mistake 4: Not adding potassium early enough Even if initial K⁺ is normal or high, replacement will be required as insulin drives K⁺ into cells.

Mistake 5: Treating HHS like DKA HHS needs slower correction over 24–72 hours, insulin is withheld until glucose stops falling with fluids alone, lower insulin dose when needed, and treatment-dose LMWH.

Mistake 6: Stopping background long-acting insulin Continue the patient's usual long-acting insulin analogue during DKA treatment to prevent rebound hyperglycaemia after IV insulin is stopped.

Mistake 7: Missing euglycaemic DKA in SGLT-2 inhibitor users If a patient on an SGLT-2 inhibitor has ketonaemia and acidosis but near-normal glucose, treat as standard DKA. The glucose threshold for diagnosis does not apply.

Biochemical Scenarios

Scenario 1: Classic DKA

• Glucose 28 mmol/L | pH 7.15 | Ketones 4.2 mmol/L | Bicarbonate 12 mmol/L

• Answer: DKA. Start IV 0.9% NaCl immediately; add FRIII at 0.1 units/kg/hour after initial fluid bolus. Monitor hourly; reduce insulin to 0.05 units/kg/hour and add 10% glucose when glucose ≤14 mmol/L.

Scenario 2: HHS

• Glucose 42 mmol/L | pH 7.36 | Ketones 0.8 mmol/L | Na⁺ 156 mmol/L | Osmolality 362 mOsm/kg

• Answer: HHS. Cautious IV 0.9% NaCl (aim osmolality fall 3–8 mOsm/kg/hour). Withhold insulin until glucose stops falling with fluids alone. Treatment-dose LMWH.

Scenario 3: Mixed DKA/HHS

• Glucose 35 mmol/L | pH 7.22 | Ketones 2.5 mmol/L | Osmolality 335 mOsm/kg

• Answer: Mixed picture. Ketones <3.0 mmol/L but acidosis present — seek early specialist input. If ketones were >3.0 mmol/L, default to DKA protocol but be mindful of correction rate given elevated osmolality.

Scenario 4: Euglycaemic DKA (new — SGLT-2 inhibitor)

• Glucose 9 mmol/L | pH 7.18 | Ketones 4.5 mmol/L | Patient on empagliflozin

• Answer: Euglycaemic DKA. Treat as standard DKA. Stop SGLT-2 inhibitor. Glucose threshold for DKA diagnosis does not apply here.

Summary of Key Numbers

Study Strategy for DKA/HHS

Focus areas for FRCEM SBAs:

• Diagnostic criteria (exact numbers — especially the updated HHS threshold: ketones ≤3 mmol/L)

• The 2023 insulin de-escalation rule (0.1 → 0.05 units/kg/hour at glucose ≤14 mmol/L)

• Fluid protocols (0.9% NaCl first-line for both; when to consider 0.45% in HHS)

• Potassium replacement protocol

• When to add 10% glucose (glucose ≤14 mmol/L, alongside — not instead of — continued insulin)

• Resolution criteria for DKA vs HHS (different parameters)

• HHS-specific: withhold insulin initially, treatment-dose anticoagulation, 24–72 hr correction

• Euglycaemic DKA in SGLT-2 inhibitor users

• ICU escalation criteria

Practice approach: work through 30–40 DKA/HHS questions covering biochemistry interpretation, complications, and management steps. Pay particular attention to scenarios involving glucose ≤14 mmol/L — the FRIII de-escalation is the most commonly updated and examined change.

DKA and HHS questions test systematic understanding of diabetic emergency management following current guidelines. The 2021–2023 JBDS updates introduced two key changes you must know: (1) de-escalate insulin from 0.1 to 0.05 units/kg/hour when glucose ≤14 mmol/L in DKA, and (2) HHS resolution criteria now include osmolality <300 mOsm/kg, not just glucose correction.

Master diagnostic criteria, fluid protocols, insulin dosing, potassium management, and complication recognition to secure reliable marks on these predictable, high-yield questions.

Guidelines referenced:

• JBDS 02: Management of Diabetic Ketoacidosis in Adults, Revised March 2023 — abcd.care

• JBDS 06: Management of Hyperosmolar Hyperglycaemic State (HHS) in Adults, February 2022 — abcd.care