Toddler with Diabetic Ketoacidosis and Altered Mental Status
A 4-year-old boy weighing 16 kg is brought to the emergency department with 2 days of vomiting, abdominal pain, and progressive lethargy. He was diagnosed with type 1 diabetes 8 months ago and uses insulin glargine and aspart. His parents report he has had poor intake and his insulin pump was removed 2 days ago because of a site infection. Vital signs: temperature 37.1°C, heart rate 132/min, respiratory rate 32/min and deep, blood pressure 88/54 mmHg, SpO2 99% on room air. He is drowsy but arousable, with dry mucous membranes and capillary refill of 3 seconds. Point-of-care glucose is 512 mg/dL. Venous blood gas: pH 7.12, PCO2 22 mmHg, bicarbonate 8 mmol/L. Beta-hydroxybutyrate is 5.8 mmol/L. Sodium is 132 mmol/L, potassium 4.9 mmol/L, chloride 100 mmol/L, BUN 22 mg/dL, creatinine 0.6 mg/dL. Urinalysis shows 4+ ketones and 3+ glucose.
1. Calculate and justify the initial fluid and insulin plan for the first 6 hours.
Read the worked answer
This is moderate-to-severe diabetic ketoacidosis with dehydration and acidosis. The priorities are volume resuscitation, then insulin, with careful attention to potassium and to the risk of cerebral edema.
Fluids: give an initial 10–20 mL/kg isotonic crystalloid bolus (160–320 mL of 0.9% saline) over 30–60 minutes and reassess perfusion. Then calculate the deficit: assume 5–10% dehydration, so about 800–1,600 mL, and replace it evenly over 24–48 hours along with maintenance. A practical approach is maintenance plus deficit replacement using 0.45–0.9% saline with potassium added once the patient is making urine and potassium is below the upper limit. Avoid rapid large-volume boluses beyond the initial resuscitation, because rapid fluid administration is associated with cerebral edema.
Insulin: start a continuous infusion of regular insulin at 0.05–0.1 units/kg/h (0.8–1.6 units/h) after the initial fluid bolus. Do not give a subcutaneous insulin bolus if an infusion is being started. Continue the infusion until the acidosis resolves (pH above 7.30, bicarbonate above 15, and beta-hydroxybutyrate below 0.6 mmol/L), not merely until glucose normalizes. Add dextrose (5% or 10%) to the IV fluids when glucose falls to about 250–300 mg/dL so the insulin can continue clearing ketones.
Potassium: the serum potassium of 4.9 mmol/L will fall with insulin and fluids. Add 20–40 mEq/L of potassium chloride (or potassium phosphate if phosphate is low) once urine output is confirmed and potassium is below 5.5 mmol/L, and monitor every 2–4 hours.
Monitoring: hourly glucose, neurological checks, strict intake and output, and repeat electrolytes, blood gas, and beta-hydroxybutyrate every 2–4 hours. Avoid bicarbonate unless pH is severely low and the patient is in shock, because it can worsen cerebral edema and hypokalemia.
2. Four hours into treatment, the boy becomes more drowsy and complains of a severe headache. Glucose has fallen from 512 to 240 mg/dL. What is your concern and what will you do?
Read the worked answer
The concern is cerebral edema, the most dangerous complication of pediatric DKA. Warning signs include headache, altered mental status, bradycardia, hypertension, pupillary changes, and declining oxygen saturation. The timing - a few hours into treatment as glucose falls - is typical. This is a clinical diagnosis; do not delay treatment for imaging.
Immediate actions: elevate the head of the bed, ensure airway protection, and give hypertonic therapy. Give 3% saline at 2.5–5 mL/kg over 10–15 minutes, or mannitol 0.5–1 g/kg IV over 10–15 minutes; many centers prefer hypertonic saline. Reduce the fluid infusion rate to a maintenance rate and slow the rate of glucose decline. Do not stop insulin entirely unless glucose is very low; instead increase dextrose in the fluids to keep glucose stable while insulin continues to clear ketones. Recheck electrolytes, glucose, and blood gas, and obtain urgent neurology and critical care consultation. Prepare for intubation if mental status deteriorates, but avoid hyperventilation unless there is impending herniation.
Review what may have contributed: excessive fluid boluses, too-rapid correction of hyperglycemia, or a rapid drop in osmolality. Going forward, keep glucose decline to roughly 50–100 mg/dL per hour, use isotonic fluids for maintenance where possible, and reassess neurological status hourly. Document the event and inform the family. After recovery, arrange diabetes education about sick-day rules and pump-site care, since the pump removal without a basal insulin plan likely precipitated this episode.
3. The parents ask why the team is 'not just giving a lot of insulin to bring the sugar down fast.' Explain the physiologic reasoning and the discharge safety plan.
Read the worked answer
Explain that the high sugar is a symptom; the real problem is that without insulin the body burns fat and makes acids called ketones, which make the blood acidic. Insulin is needed to stop ketone production, but giving large doses quickly can drop the sugar and the salt concentration in the blood too fast, which pulls water into the brain and causes swelling - the headache and drowsiness we just treated. So the team gives insulin steadily and adds sugar to the IV fluids once the glucose comes down, so insulin can keep working on the ketones without dropping the glucose too low.
Also explain that potassium shifts into cells when insulin is given, so potassium must be checked and supplemented; dangerously low potassium can affect the heart.
Discharge safety plan: teach sick-day rules - never stop basal insulin, check ketones with every illness or glucose above 250 mg/dL, and call the diabetes team early. Review pump-site care and have a backup plan using long-acting insulin and a pen if the pump fails. Provide written instructions with doses, a glucose meter and ketone strips, and an emergency contact. Arrange a diabetes educator visit and a follow-up appointment within a week. Ask the parents to teach back the sick-day plan and confirm they can check ketones and give a correction dose. Document the teaching and the family's understanding.