New-Onset Diabetes in DKA Who Develops a Headache at Hour Six
An 11-year-old, 38.4 kg, is brought in at 07:00 after three weeks of polyuria and polydipsia, 4 kg of weight loss and 24 hours of vomiting. He is drowsy but rousable, breathing deep and fast with a fruity odour. HR 128, RR 32, BP 102/64, temperature 37.4 °C, GCS 15. Point-of-care glucose 32 mmol/L (576 mg/dL), venous pH 7.09, pCO₂ 22 mmHg, bicarbonate 8 mmol/L, potassium 5.6 mmol/L, sodium 131 mmol/L, chloride 98 mmol/L, BUN 9.8 mmol/L, creatinine 88 µmol/L, beta-hydroxybutyrate 5.8 mmol/L. Urine ketones are large. He has never been diagnosed with diabetes.
1. Outline your initial fluid and insulin plan with rationale, and state what you are deliberately not giving.
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Fluids
- 10 mL/kg (about 384 mL) of 0.9% sodium chloride over 30–60 minutes. Repeat 10–20 mL/kg only if there is shock (he is currently normotensive).
- Then calculate rehydration: estimated deficit (5–10%) plus maintenance (4-2-1 gives roughly 78 mL/h) delivered evenly over 48 hours, using 0.9% sodium chloride with potassium added once the potassium is below 5.5 mmol/L and urine output is documented.
- Avoid a rapid or hypotonic rehydration strategy; the rate is a treatment decision, not a convenience.
Insulin
- Regular insulin infusion at 0.05–0.1 units/kg/h (about 2–4 units/h), started at least one hour after fluid resuscitation begins.
- No insulin bolus. A bolus increases the risk of cerebral oedema without improving ketone clearance.
- Target a glucose fall of roughly 2–5 mmol/L per hour. When glucose reaches about 14–15 mmol/L, add dextrose to the fluids and continue insulin until the ketones clear - never stop insulin to treat a falling glucose.
Deliberately not giving
- Sodium bicarbonate: at pH 7.09 there is no indication, and it increases the risk of cerebral oedema, hypokalaemia and paradoxical CSF acidosis. Reserve it for pH below 6.9 with cardiac compromise.
- Subcutaneous long-acting insulin or a bolus, until the acidosis has resolved and the child is eating.
- Potassium in the first bolus while the potassium is 5.6 mmol/L.
Monitoring that goes with the order: hourly glucose, two-hourly electrolytes and venous gas, hourly neurological checks, strict intake and output, and continuous cardiac monitoring.
2. Potassium is 5.6 mmol/L. Should you add potassium to the fluids? Explain the paradox and outline the plan for the next few hours.
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The paradox. This potassium looks high but reflects total body depletion of roughly 3–5 mmol/kg. Insulin deficiency, hypertonicity and acidosis shift potassium out of cells. Once insulin and fluids are started, potassium moves back into cells and can fall precipitously, with a risk of life-threatening hypokalaemia and arrhythmia.
Plan
- Do not add potassium to the initial resuscitation bolus, and do not add it until the potassium is below 5.5 mmol/L and urine output is documented.
- Then add about 40 mmol/L of potassium to the rehydration fluids (commonly two-thirds potassium chloride, one-third potassium phosphate).
- Check potassium every two hours while the infusion runs, and watch the ECG for peaked T waves (hyperkalaemia) or flattened T waves and U waves (hypokalaemia).
- Interpret the sodium: 131 mmol/L with a glucose of 32 mmol/L is partially dilutional; use a corrected value and recheck as glucose falls. A rising corrected sodium can be an early clue to cerebral oedema.
- Track the BUN (9.8 mmol/L), an independent risk marker for cerebral oedema in new-onset DKA.
Reasoning. The judgement being tested is treating the patient rather than the number - the highest risk to this child is not the potassium of 5.6 but the potassium of 2.9 three hours from now.
3. At hour six the child vomits, complains of a severe headache, becomes drowsy with a GCS of 13, and the heart rate falls from 118 to 78 with BP rising from 100/62 to 128/76. What do you do?
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This is cerebral oedema until proven otherwise. Bradycardia with rising blood pressure and a falling level of consciousness is the Cushing response - a late, pre-herniation sign. Do not wait for imaging.
Within minutes
- Call the physician and PICU immediately, and bring the airway and emergency trolley to the bedside.
- Elevate the head of the bed to 30 degrees and keep the head midline; ensure oxygenation and avoid hypotension.
- Reduce the intravenous fluid rate by one third and stop any bolus.
- Give mannitol 0.5–1 g/kg intravenously over 10–15 minutes, or 3% sodium chloride 2.5–5 mL/kg over 10–15 minutes. Use one agent, not both.
- Arrange CT head only after stabilisation; do not send an unstable child to the scanner.
- Prepare for intubation if the level of consciousness continues to fall; maintain normal ventilation rather than prolonged hyperventilation.
Risk factors present: new-onset diabetes, high BUN, severe acidosis and a rapid clinical course.
Afterwards: document the timeline second by second (onset of headache, vital sign change, time of osmotic therapy), debrief the team, and review whether hourly neurological checks with a headache assessment were being done before the deterioration. A new headache in paediatric DKA is an escalation trigger, not a minor complaint.