Prevalence of impaired awareness of hypoglycemia and identification of predictive symptoms in children and adolescents with type 1 diabetes.

BACKGROUND: In children with type 1 diabetes mellitus (T1DM) the prevalence of impaired awareness of hypoglycemia (IAH) is uncertain. This study aimed to ascertain this with greater precision. Secondary aims were to assess symptoms of hypoglycemia and which of these best predict awareness of hypoglycemia in children. METHODS: Questionnaires were completed by 98 children with T1DM (mean age 10.6 yr) and their parent(s); hospital admission data for the previous year were collected. Awareness of hypoglycemia was assessed using two questionnaire-based methods that have been validated in adults. For 4 wk, participants performed routine blood glucose measurements and completed questionnaires after each episode of hypoglycemia. Principal components analysis determined how symptoms correlate; multinomial logistic regression models identified which symptom aggregate best predicted awareness status. RESULTS: The 'Gold' questionnaire classified a greater proportion of the participants as having IAH than the 'Clarke' questionnaire (68.4 vs. 22.4%). Using the 'Clarke' method, but not the 'Gold' method, children with IAH were younger and more likely to require external assistance or hospital admission. Most aged ≥9 yr (98.6%) were able to self-assess awareness status accurately. Puberty and increasing age, augmented symptom scores; duration of diabetes and glycemic control had no effect. In contrast to adults, behavioral symptoms were the best predictors of awareness status. CONCLUSIONS: IAH affects a substantial minority of children and impending hypoglycemia may be heralded by behavioral symptoms. The 'Clarke' method was more effective at identifying those at increased risk and could be used as a screening tool.