Hypoglycemia: incidence and clinical predictors in a large population-based sample of children and adolescents with IDDM.
OBJECTIVE
To determine the frequency of moderate and severe hypoglycemia and to identify clinical predictors associated with its occurrence in a large population-based sample of children and adolescents with IDDM.


METHODS
A total of 657 patients (age: 12.1 +/- 4.4 years, mean +/- SD) were included in the study, yielding 1,449 patient-years of data. A prospective assessment of severe hypoglycemia (an event resulting in a seizure or coma) and moderate hypoglycemia (an event requiring assistance of another, excluding severe episodes) was made over a 3-year period. Patients and caregivers detailed episodes of significant hypoglycemia (moderate and severe events) and these were recorded at each 3-month clinic visit along with HbA1c. Data were analyzed using generalized estimating equation models fitted with the exchange correlation structure.


RESULTS
The overall incidence of severe events was 4.8/100 patient-years and of moderate events was 13.1/100 patient-years. Over 3 years, severe events occurred in 8.5% of children and moderate events occurred in 26.9%. Significant hypoglycemia was rare in the first 12 months after diagnosis. Rates of hypoglycemia were increased in children < 6 years of age versus > 6 years of age (40.9 vs. 16.6/100 patient-years, age < or = 6 years vs. age > 6 years, P < 0.001). Rates of hypoglycemia doubled when HbA1c fell below 8%, and children with HbA1c < 7% had a threefold increase in both moderate and severe hypoglycemia (e.g., severe episodes 14.9 vs. 4.1/100 patient-years, HbA1c < or = 7% vs. HbA1c > 7%, P < 0.001). Most severe events were seizures, and 75% of them occurred at night. The majority of events were related to missed meals or increased activity. However, in 38% no predisposing factor was evident.


CONCLUSIONS
Newly diagnosed children appear to be protected from severe hypoglycemia. Rates increase with lower glycated hemoglobin, especially when mean HbA1c is < 8.0%. Younger children, who may be more susceptible to the adverse effects of neuroglycopenia, are at a particular risk of significant hypoglycemia.
Davis
E A
EA
Department of Diabetes and Endocrinology, Princess Margaret Hospital for Children, Perth, Western Australia.
Keating
B
B
Byrne
G C
GC
Russell
M
M
Jones
T W
TW
D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D011446:Prospective Studies; D013997:Time Factors; D014904:Western Australia / Q000453:epidemiology
D006442:Glycated Hemoglobin