Incidence and predictive criteria of nocturnal hypoglycemia in young children with insulin-dependent diabetes mellitus.
OBJECTIVE
To determine the incidence of significant nocturnal hypoglycemia occurring at home in young children with insulin-dependent diabetes mellitus using conventional therapy.


METHODS
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 (HbA1c) with a greater than 50% incidence of hypoglycemia seen in subjects with HbA1c levels of less than 8.5%. The average HbA1c 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 HbA1c, 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 HbA1c concentration; the condition is often asymptomatic. Early-morning hypoglycemia is poorly predicted by a blood glucose determination at 11 PM and is not prevented by carbohydrate intake at supper. In younger children, blood glucose profiles should include early-morning measurements.
Porter
P A
PA
Department of Paediatric Endocrinology, Princess Margaret Hospital for Children, Perth, Australia.
Keating
B
B
Byrne
G
G
Jones
T W
TW
D000367:Age Factors; D001786:Blood Glucose / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000503:physiopathology*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007003:Hypoglycemia / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D015994:Incidence; D007328:Insulin / Q000627:therapeutic use; D007336:Insulin, Isophane / Q000627:therapeutic use; D008297:Male; D011237:Predictive Value of Tests
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; D007336:Insulin, Isophane