Childhood diabetes usually presents acutely with polyuria (including nocturia and incontinence), thirst and polydipsia; about 40% have diabetic ketoacidosis (DKA) (Table 28.1). Other symptoms are weight loss, fatigue and abdominal pain. A simultaneous febrile illness is noted in about 20% of cases, particularly in younger children. Other possible presenting features include muscle cramps, infections (e.g. boils, urinary tract infections), behaviour disturbance and poor school performance.
As with adults, DKA in children is a medical emergency that requires urgent admission to hospital, intravenous rehydration and insulin infusion. Severe acidosis (pH < 7.0) is life-threatening. Unless there is initial hyperkalaemia, potassium is added early, at the rate of 20 mmol/L of saline, because the serum K+ concentration is likely to fall during insulin replacement. The usual rate of insulin infusion is 0.1 U/kg/h or 0.05 U/kg/h in the child <5 years of age. The initial saline infusion should be replaced by 5% glucose (dextrose) when the plasma glucose reaches about 14 mmol/L (Figure 28.4).
The most common cause of death during DKA in children is cerebral edema, which leads to herniation of the brain-stem, extension of the cerebellar tonsils into the foramen magnum and respiratory arrest (Figure 28.5). It is diagnosed by magnetic resonance imaging or computed tomography of the brain. Clinically, there is headache, depressed consciousness and sometimes papilledema. Cerebral edema is unpredictable but more common in younger children, and carries a mortality of 25%. Risk factors include low arterial PCO2, elevated blood urea and treatment with bicarbonate. Over-rapid delivery of fluid and insulin might be involved also. The treatment involves intravenous mannitol (20% mannitol, 2.5 mL/kg over 15 minutes, repeated if necessary) or use of hypertonic saline. Other causes of death include aspiration pneumonia and hypokalemia.