Impaired Awareness of Hypoglycemia in a Population-Based Sample of Children and Adolescents With Type 1 Diabetes

OBJECTIVE To determine the prevalence and clinical associations of impaired awareness of hypoglycemia in a population-based sample of children and adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS A validated questionnaire was administered to 656 patients with type 1 diabetes over a 6-month period to determine hypoglycemia awareness status. Case ascertainment was 79% of the clinic population. The rate of severe hypoglycemia was determined by data collected prospectively in the preceding year. RESULTS Impaired awareness of hypoglycemia was present in 29% of patients. Patients with impaired awareness of hypoglycemia had an earlier onset of diabetes (P < 0.001), were younger (P < 0.001), and had lower mean levels of A1C since diabetes onset (P = 0.006) and at their last visit (P = 0.001). The overall rate of severe hypoglycemia was 24.5 episodes per 100 patient-years in the preceding year. The severe hypoglycemia rate was higher in those with impaired awareness of hypoglycemia (37.1 vs. 19.3 episodes per 100 patient-years, P < 0.001). Among patients aged <6 years (n = 46), 59% of care providers reported impaired awareness of hypoglycemia, and the rate of severe hypoglycemia was significantly higher in those reporting impaired awareness (33.3 vs. 52 episodes per 100 patient-years, P = 0.02). More patients with recurrent hypoglycemia reported impaired awareness of hypoglycemia (47 vs. 28%, P = 0.03). CONCLUSIONS A significant proportion of children and adolescents with type 1 diabetes have impaired awareness of hypoglycemia. Screening for impaired awareness is an important component of routine diabetes care and can identify patients at increased risk of a severe hypoglycemic event.