Type 1 diabetes: insulin therapy, technology and ambulatory care — branching viva

Branch 1 — Opening: the principle that governs everything

Examiner: "A nine-year-old with type 1 diabetes developed ketoacidosis during a viral illness because her parents stopped her insulin. State the single principle that was broken, and explain the rationale." [2]

Expected: Insulin is never stopped during an intercurrent illness. Fever, infection and the stress response raise insulin needs, so the dose is usually increased; withholding insulin is the commonest precipitant of sick-day ketoacidosis. [2]

Branch probes (examiner selects based on the answer): [2]

• If the candidate states the principle well, outline the sick-day routine the family should have followed: check glucose every 2–4 hours; check blood ketones at every glucose check; hydrate with small frequent carbohydrate-containing fluids; give extra rapid-acting insulin for hyperglycaemia with ketones per the plan; never omit basal insulin. [2]
• If the candidate hesitates, state the ketone threshold and clinical signs that should have sent them to hospital before she became acidotic: blood ketones above 1.5 mmol/L and rising; vomiting preventing fluid retention; deep or rapid breathing; drowsiness; persistent hyperglycaemia above 15–20 mmol/L. [2]

Branch 2 — The pump child with ketones

Examiner: "Now a seven-year-old on a pump for two years, six hours of abdominal pain, glucose 19 mmol/L, ketones 2.8 mmol/L. The cannula site looks normal, reservoir half full. Why can she be ketotic this fast, and what do you do?" [3]

Expected: A pump carries no long-acting basal depot, only a rapid analogue through the cannula; a blocked or dislodged cannula removes all insulin within hours even when the site looks normal. Immediate management is to give a rapid-acting insulin correction by pen and change the infusion set. [3]

Branch probes: [3]

• If the candidate simply raises the basal rate, the suspect site still fails to deliver, ketones climb, and ketoacidosis worsens. [3]
• Escalate to a full DKA pathway if ketones rise despite the correction, vomiting persists, or the pH falls. [2]

Branch 3 — Swinging glucose and firm nodules

Examiner: "An eleven-year-old, correct regimen, reliable carb counting, but glucose swings wildly and she has firm nodules at her injection sites. What is the diagnosis and the management?" [1]

Expected: Lipohypertrophy from poor site rotation causes erratic and unpredictable insulin absorption and is a leading correctable cause of unstable control. The management is to teach systematic site rotation and avoid injecting into the nodules, which restores absorption predictability. [1]

Branch 4 — Loss of hypoglycaemia awareness

Examiner: "A sixteen-year-old, three severe lows in six months, no longer feels the warning symptoms, HbA1c 6.4 percent. What has happened and what is your next step?" [5]

Expected: Recurrent hypoglycaemia has produced impaired awareness, which predicts the next severe event. The correct step is to raise glycaemic targets temporarily to restore awareness before any tightening — not to lower the target further or increase insulin. [5]

Branch 5 — Targets, technology and transition

Examiner: "Close with the headline targets and the trial you would cite to a family considering closed-loop for their young child." [5]

Expected: The targets are an HbA1c below 7 percent (53 mmol/mol) and a time-in-range above 70 percent with time-below-range below 4 percent. For closed-loop in young children, cite the Wadwa trial of hybrid closed-loop control in young children, noting that automated insulin delivery extends to the two-to-six age group with the meal bolus remaining manual. [4]

Closing probe: When she reaches sixteen, a structured transition beginning in the early to mid-teens, with joint clinics, skills checklists and a formal handover summary, prevents her being lost at the adult handover. [1]