Incidence and predictive criteria of nocturnal hypoglycemia in young children with insulin-dependent diabetes mellitus

Abstract

Objective: To determine the incidence of significant nocturnal hypoglycemia occurring at home in young children with insulin-dependent diabetes mellitus using conventional therapy. Design: Sixty-one children (aged 2.6 to 8.5 years) were studied on one night, at home, with blood collection occurring at dinner, bedtime/supper, 11 pm , 2 am , and breakfast, with subsequent laboratory analysis. Results: The proportion of subjects 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%, respectively. Nocturnal hypoglycemia was associated with younger age (<5 years 57% vs 5 to 8.5 years 36%; p <0.001) and lowered glycosylated hemoglobin levels (HbA 1c ) with a greater than 50% incidence of hypoglycemia seen 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 nonhypoglycemic group (7.8 vs 8.3%; p <0.02). Nocturnal hypoglycemia occurred with increasing frequency throughout the night in subjects less than 5 years of age (dinner, supper, 11 pm , 2 am , and breakfast incidences being 0%, 12.5%, 26%, 33%, and 30%, respectively) but not in those older than 5 years. Carbohydrate intake at supper did not prevent subsequent hypoglycemia. Blood glucose levels at 11 pm were poor predictors 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 nocturnal 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 insulin-dependent diabetes mellitus receiving conventional therapy is unacceptably high and is increased with lowered age and HbA 1c concentration; the condition is often asymptomatic. Early-morning hypoglycemia is poorly predicted by a blood glucose determination at ll pm and is not prevented by carbohydrate intake at supper. In younger children, blood glucose profiles should include early-morning measurements. (J Pediatr 1997;130:366-72)