Type 1 diabetes: diagnosis and initial management — formative SAQs

SAQ 1 — The alert child with new hyperglycaemia (10 marks)

A 6-year-old presents with a two-week history of excessive thirst, frequent urination and a 2 kg weight loss. He is alert, well perfused and tolerating oral fluids. The finger-prick glucose is 22 mmol/L. He has no vomiting, no abdominal pain and normal breathing. This is the classic presentation of new-onset type 1 diabetes without ketoacidosis. [1]

Answer the following

1. State the criteria by which you can confirm the diagnosis of diabetes in this child. [2]
2. Describe the single most important assessment you must make before deciding on the treatment pathway, and how you make it. [1]
3. Outline the initial insulin regimen you would start once ketoacidosis is excluded, including the approximate dose. [3]
4. List four components of the structured education the family needs before discharge. [3]

Model marking guide

1. Diabetes is confirmed on glucose: a random plasma glucose of 11.1 mmol/L or higher with classic symptoms (met here at 22 mmol/L), or a fasting plasma glucose of 7.0 mmol/L or higher, or an HbA1c of 48 mmol/mol (6.5 percent) or higher. In a symptomatic child a single high reading is sufficient to diagnose and act. [2]
2. The critical assessment is to exclude diabetic ketoacidosis, because acidosis diverts the child to a different pathway. Measure capillary or blood ketones together with venous pH and bicarbonate, and assess hydration, conscious level and respiratory pattern. An alert, non-acidotic child with only mildly raised ketones is suitable for the uncomplicated subcutaneous pathway. [1]
3. Start a subcutaneous basal-bolus regimen: a total daily dose of about 0.5 to 1.0 units per kilogram per day, split roughly half basal (a once or twice daily long-acting analogue) and half bolus (a rapid analogue with each meal), titrated to the glucose pattern. [3]
4. Any four of: blood glucose monitoring; carbohydrate counting and meal-time dosing; recognition and treatment of hypoglycaemia with fast-acting carbohydrate; sick-day rules built on never stopping insulin; insulin injection technique and site rotation; when and who to contact. [3]

SAQ 2 — Type, honeymoon and the never-stop rule (10 marks)

A 13-year-old girl presents with polyuria, polydipsia and weight loss and a random glucose of 19 mmol/L. She is overweight with mild acanthosis nigricans, and her mother has type 2 diabetes. She is alert and not acidotic. You start insulin and send confirmatory tests. Six weeks later her insulin requirement has fallen sharply and her glucose readings are excellent. [4]

Answer the following

1. Explain which tests will confirm whether she has type 1 or type 2 diabetes, and what result would indicate each. [4]
2. Justify why you started insulin before those results were available. [1]
3. Explain the fall in her insulin requirement at six weeks and name the phase. [5]
4. State the single most important instruction to the family about insulin during this phase, and the reason. [5]

Model marking guide

1. Islet autoantibodies (GAD, IA-2, ZnT8, IAA) and C-peptide. Two or more positive autoantibodies with a low C-peptide relative to glucose indicate type 1 diabetes; negative autoantibodies with a preserved or high C-peptide, in this phenotype, indicate type 2 diabetes. The results are read together with the clinical picture. [4]
2. In a symptomatic hyperglycaemic child the diagnosis of diabetes is made on glucose alone, and the type-defining tests take days to return. Starting insulin cannot wait, because under-treating a true type 1 risks progression to ketoacidosis; an uncertain type is treated as type 1 until results clarify. [1]
3. As the acute glucose toxicity settles and surviving beta cells recover after treatment begins, endogenous insulin secretion partially returns and the exogenous insulin requirement falls. This is the honeymoon phase (partial remission). [5]
4. Insulin is never stopped, however small the dose. The honeymoon is temporary, the beta cells will fail again, and stopping insulin is a direct route back to ketoacidosis; the family should understand it as a reprieve, not a cure. [5]