Classification of hypoglycemia awareness in people with type 1 diabetes in clinical practice

Aim: No consensus exists on classification of hypoglycemia awareness. We compared three methods for assessment of hypoglycemia awareness in a clinical setting. Methods: A questionnaire including the three methods was filled in by 372 outpatients with Type I diabetes [43% women, age 51 +/- 14 years (mean +/- S.D.)], duration of diabetes 24 +/- 13 years, and hemoglobin A1c 8.2 +/- 1.0%). Method A (Diabetes Care, 17, 697-703) and B (Diabetes Care, 18, 517-522) classify into two degrees of awareness, while Method C (Diabetes/Metabolism Research and Reviews, 19, 232-240) includes three classes. Results: Normal awareness was reported in 75%, 51%, and 41% (A, B, C); 25% and 28% had impaired awareness (A, B); and 13% were unaware (C); 46% belonged to the intermediate class of impaired awareness (C), while 21% were not classifiable (B). Higher rates of severe hypoglycemic events were reported by patients with impaired awareness (A, B) and unawareness (C) compared to aware patients. Patients with impaired awareness (C) had more severe hypoglycemia than aware patients and less severe hypoglycemia than unaware patients. A lower rate of severe hypoglycemia was reported by aware patients classified by Method C than A. Fractions of patients with normal awareness without an event of severe hypoglycemia were 0.81, 0.86, and 0.91 (A, B, C). Conclusion: All three methods for assessment of hypoglycemia awareness are feasible in clinical practice since the degree of awareness is associated with risk of severe hypoglycemia. The trisected method (C) identifies an intermediate group with impaired awareness and with a risk of severe hypoglycemia that is significantly different from those of aware and unaware patients. (C) 2010 Elsevier Inc. All rights reserved.