INCIDENCE AND PREDICTIVE CRITERIA OF NOCTURNAL HYPOGLYCEMIA IN YOUNG-CHILDREN WITH INSULIN-DEPENDENT DIABETES-MELLITUS

Objective: To determine the incidence of significant nocturnal hypogly cemia occurring at home in young children with insulin-dependent diabe tes mellitus using conventional therapy. Design: Sixty-one children (a ged 2.6 to 8.5 years) were studied on one night, at home, with blood c ollection occurring at dinner, bedtime/supper, 11 PM, 2 AM, and breakf ast, with subsequent laboratory analysis. Results: The proportion of s ubjects with blood glucose levels less than 64, 55, 45, and 36 mg/dl ( 3.5, 3.0, 2.5, and 2.0 mmol/L) was 37.8%, 17%, 13%, and 8%, respective ly. Nocturnal hypoglycemia was associated with younger age (<5 years 5 7% vs 5 to 8.5 years 36%; p <0.001) and lowered glycosylated hemoglobi n levels (HbA(1c)) with a greater than 50% incidence of hypoglycemia s een in subjects with HbA(1c) levels of less than 8.5%. The average HbA (1c) concentration was lower in the hypoglycemic group than in the non hypoglycemic group (7.8 vs 8.3%; p < 0.02). Nocturnal hypoglycemia occ urred with increasing frequency throughout the night in subjects less than 5 years of age (dinner, supper, 11 PM, 2 AM, and breakfast incide nces being 0%, 12.5%, 26%, 33%, and 30%, respectively) but not in thos e older than 5 years. Carbohydrate intake at supper did not prevent su bsequent hypoglycemia. Blood glucose levels at 11 PM were poor predict ors of subsequent hypoglycemia at 2 AM in either the group as a whole or in the children less than 5 years of age. Symptom recognition of no cturnal hypoglycemia was decreased in younger children (<5 years (36%) >5 years (58%)), in those with a lower HbA(1c), and when hypoglycemia occurred at breakfast rather than at dinner (0% vs 50%). Conclusions: The incidence of nocturnal hypoglycemia in young children with insuli n-dependent diabetes mellitus receiving conventional therapy is unacce ptably high and is increased with lowered age and HbA(1c) concentratio n; the condition is often asymptomatic. Early-morning hypoglycemia is poorly predicted by a blood glucose determination at II PM and is not prevented by carbohydrate intake at supper. In younger children, blood glucose profiles should include early-morning measurements.