Type 1 diabetes: diagnosis and initial management — branching viva

Branch 1 — Opening: confirm and triage

Examiner: "A six-year-old has two weeks of thirst, polyuria and weight loss and a finger-prick glucose of 22 mmol/L. How do you confirm the diagnosis, and what is the single most important thing you must decide next?" [2]

Expected: The diagnosis of diabetes is confirmed on glucose — a random level of 11.1 mmol/L or higher with symptoms (met here), a fasting level of 7.0 or higher, or an HbA1c of 48 mmol/mol (6.5 percent) or higher. The most important next decision is whether the child has ketoacidosis, because that changes the whole pathway. [2] [1]

Branch probes (examiner selects based on the answer): [1]

• If the candidate confirms and triages well, state how you exclude ketoacidosis: measure capillary or blood ketones with venous pH and bicarbonate, and assess hydration, conscious level and breathing. [1]
• If the candidate wants to wait for antibody results before treating, correct them: the diagnosis is made on glucose alone and treatment must not wait for the type-defining tests. [4]

Branch 2 — Starting treatment

Examiner: "He is alert, not acidotic, with only mildly raised ketones. Outline your initial treatment." [3]

Expected: Maintain oral hydration and start a subcutaneous basal-bolus insulin regimen — a total daily dose of about 0.5 to 1.0 units per kilogram per day, split roughly half basal (long-acting analogue) and half bolus (rapid analogue with meals) — alongside structured family education on monitoring, carbohydrate counting, hypoglycaemia and sick-day rules. [3]

Branch probes: [3]

• If the candidate reaches for intravenous insulin, note that an intravenous infusion is for ketoacidosis; this alert non-acidotic child is managed with subcutaneous insulin. [3]
• If asked about disposition, either a brief admission for stabilisation and education or, in experienced ambulatory services, home management is acceptable, depending on local resources. [1]

Branch 3 — The adolescent: which type?

Examiner: "Now a thirteen-year-old, overweight with acanthosis nigricans, glucose 19 mmol/L, mother has type 2 diabetes. How do you decide the type, and does it change your immediate treatment?" [4]

Expected: Send islet autoantibodies and C-peptide: two or more positive antibodies with a low C-peptide indicate type 1, while negative antibodies with a preserved C-peptide in this phenotype indicate type 2. It does not change the immediate treatment — she is treated with insulin as type 1 until the results clarify, because under-treating a true type 1 is dangerous. [4] [1]

Branch 4 — The infant

Examiner: "A four-month-old infant is found to have persistent hyperglycaemia. What is the diagnosis you must consider, and why does it matter?" [1]

Expected: Diabetes under six months of age is neonatal (monogenic) diabetes, not type 1. It matters because genetic testing is essential and some forms, such as activating potassium-channel mutations, respond to an oral sulfonylurea rather than lifelong insulin. [4] [1]

Branch 5 — The well relative and the honeymoon

Examiner: "Finally, the well younger sibling of a child with type 1 diabetes is found to have two islet autoantibodies with normal glucose. What does this mean, and what can be offered? And briefly, what will you tell the six-year-old's family when his insulin dose falls in a few weeks?" [5]

Expected: The sibling has stage 1 preclinical type 1 diabetes and needs education and metabolic surveillance, not reassurance; in stage 2, therapy that delays clinical onset, such as teplizumab in at-risk relatives, may be considered. For the six-year-old, a falling insulin dose is the honeymoon (partial remission); insulin is reduced but never stopped, because the honeymoon is temporary and stopping insulin leads back to ketoacidosis. [5] [1]