PLAB 2 DKA Station: How to Approach, Mark Scheme & Free Practice

Hold these differentials in your head

Bracket the deadly causes first. If you fail to consider any of these in your reasoning out loud, the clinical-management domain will suffer.

• Diabetic ketoacidosis (DKA)
  The diagnosis PLAB 2 is testing - a known or new type 1 diabetic with polyuria, polydipsia, vomiting, abdominal pain and dehydration, with high glucose, raised ketones and acidosis on the blood gas. Ask directly about missed insulin.
• Hyperosmolar hyperglycaemic state (HHS)
  Usually an older type 2 diabetic, developing over days rather than hours, with profound dehydration, very high glucose and drowsiness or confusion, but without significant ketones or acidosis.
• Sepsis with hyperglycaemia
  Any infection pushes glucose up in a diabetic, and infection is itself a classic DKA trigger. Screen for fever, cough, urinary symptoms and skin or foot infection - the two can coexist, and both need treating.
• Gastroenteritis in a diabetic
  Vomiting and abdominal pain look identical from the doorway, but a vomiting diabetic who stops eating and stops insulin slides into DKA fast. Never label it a stomach bug until glucose, ketones and a gas are checked.
• First presentation of type 1 diabetes
  Weight loss, thirst and passing large volumes of urine over weeks in a young patient with no diabetic history. Around a quarter of new type 1 diagnoses present in DKA - the absence of a known diagnosis excludes nothing.
• Alcoholic or starvation ketosis
  Ketones and acidosis after heavy drinking or prolonged fasting, but the glucose is normal or low rather than high. Distinguishable on the bedside glucose alone.
• Acute surgical abdomen
  DKA itself causes generalised abdominal pain and vomiting that settles with treatment, but appendicitis or pancreatitis can trigger DKA. Ask the examiner for abdominal findings before blaming the pain on the ketones.

Step-by-step approach

This is the structure that scores. You do not need to follow it verbatim, but every numbered block below maps to a cluster of marks in the rubric.

1. 1. Open the consultation and hear the agenda

   This patient often opens by asking to leave. Do not launch into a checklist over the top of her.

   • Wash hands, greet, introduce yourself with name and grade, confirm her identity.
   • Acknowledge her wish to go home before anything else - "I can hear this is really important to you. Can I ask a few questions first so we can work out the safest plan together?"
   • Agree a shared agenda: understand what happened, then talk about going home.

2. 2. Take the symptom history

   Cover the classic DKA cluster explicitly - each symptom is a mark.

   • Abdominal pain - site, onset, character, whether it is getting better or worse.
   • Nausea and vomiting.
   • Polyuria and polydipsia - passing more urine than usual, unusual thirst, drinking much more.
   • Fruity or sweet smell on the breath, deep or rapid breathing.
   • Dehydration and severity markers - dry mouth, tiredness, drowsiness or confusion, recent weight loss.

3. 3. Screen for the precipitant

   Something caused this episode. Finding it is one of the heaviest-weighted blocks in the station.

   • Missed or reduced insulin - ask directly: "Have you been able to take your insulin as usual recently?"
   • If doses were missed, gently explore why - stress, cost, illness, or deliberately skipping insulin to lose weight. Stay warm and non-judgemental; the honest answer only comes out if you make it safe to say.
   • Infection screen - fever, cough, flu-like symptoms, burning on passing urine, skin or foot problems.
   • Recent illness, vomiting, new medications such as steroids, alcohol, recreational drugs, and pregnancy in a woman of childbearing age.

4. 4. Diabetes history and insulin regimen

   Establish the background so your explanation and plan land on the right patient.

   • Type of diabetes and how long she has had it.
   • Usual insulin regimen - which insulins, when, and whether she knows her doses.
   • Recent home glucose readings and how often she checks.
   • Complications and follow-up - eye and foot problems, kidney trouble, annual review, previous DKA admissions.
   • Other conditions, medications and allergies, plus a brief social history - who is at home, work, smoking, alcohol.

5. 5. Ideas, concerns and expectations - why does she want to leave?

   The reason is nearly always concrete and human: a wedding, childcare, work. Explore it, do not lecture over it.

   • "Help me understand what is pulling you home right now."
   • Acknowledge the pressure as real and legitimate before you answer it.
   • Note the specific worries - they become the raw material for your compromise later.

6. 6. Request observations and results from the examiner

   State out loud what you want - nothing is volunteered.

   • Vital signs - blood pressure, heart rate, respiratory rate, oxygen saturation, temperature, capillary glucose.
   • Blood gas, blood ketones or urine dip for ketones, and bloods - the trio that confirms DKA.
   • General and abdominal examination findings, and an ECG if the potassium is abnormal or you are starting treatment.
   • Interpret briefly for the examiner: high glucose plus ketones plus acidosis confirms DKA.

7. 7. Explain the diagnosis in plain English and why it is dangerous

   This explanation is what changes her mind - it carries safety-critical weight, so give it time.

   • "Without insulin, your body cannot use sugar for energy, so it burns fat instead. That releases acids called ketones, and right now there is acid building up in your blood."
   • Be honest about severity without scaremongering: "This condition is called diabetic ketoacidosis. It is serious - left untreated it can be life-threatening - but it is very treatable if we act now."
   • Pause and check understanding before moving to the plan.

8. 8. Outline the management and what staying actually means

   Translate the treatment into a concrete, time-bound picture - vagueness feeds the urge to leave.

   • Fluids through the drip to correct dehydration, and insulin given through the vein to switch off ketone production.
   • Regular blood tests to monitor glucose, ketones and potassium, which can drop during treatment, with close nursing observation.
   • Treating whatever triggered the episode, and a review by the diabetes team before discharge.
   • Give a realistic timeframe - typically a short admission of a day or two once the ketones clear - so staying feels finite, not open-ended.

9. 9. If she still wants to leave: capacity, honesty, compromise, senior

   This is the safety-critical fork. You may not agree to discharge, and you may not coerce.

   • Explain the specific risks of leaving in plain words - the acid can worsen quickly, causing collapse, coma or death.
   • Problem-solve her actual barriers: offer to phone her partner or family about childcare, involve the nursing team, be creative about the practicalities.
   • If she still insists, say you would assess her capacity to make this decision and involve your senior before anything is signed.
   • Never abandon her - even a patient leaving against advice gets safety-netting, insulin advice and a clear route back.

10. 10. Safety-net, sick-day rules and close

    Prevention of the next episode is a scored block, whichever way the conversation went.

    • Sick-day rules: never stop insulin, even when not eating; check glucose and ketones more often when unwell; seek help early if vomiting or ketones rise.
    • If she skipped insulin to lose weight, address it gently and offer safer support - dietitian and diabetes-team input - without judgement.
    • Warning symptoms to report immediately: worsening tummy pain, vomiting, drowsiness, deep breathing.
    • Check understanding, invite questions, thank her and close.

Common pitfalls

• Launching into the medical history without first acknowledging her wish to leave - you lose her cooperation and the interpersonal marks in the opening minute.
• Failing to ask directly about missed insulin doses - the single heaviest data-gathering item, and the patient will not volunteer it.
• Uncovering that she skipped insulin but never asking why - the reason (stress, weight loss, cost) drives both the mark scheme and the counselling.
• Reacting with visible judgement when she admits skipping insulin to lose weight - stay warm, or she shuts down.
• Agreeing she can go home while in active DKA - a safety-critical fail regardless of everything else.
• Threatening or coercing her to stay instead of assessing capacity, explaining risks and escalating to a senior.
• Explaining the treatment in jargon - "IV fluids, fixed-rate insulin, VBG monitoring" means nothing to her; say drip, insulin through the vein, regular blood tests.
• Forgetting sick-day rules and follow-up - the station rewards preventing the next DKA, not just treating this one.

Frequently asked questions