We thank Pedersen-Bjergaard et al. (1) for their comments regarding our study (2). In our study, the ability of three methods (Gold et al. [3], Clarke et al. [4], and Pedersen-Bjergaard et al. [5]) to identify impaired awareness of hypoglycemia (IAH) in people with type 1 diabetes was evaluated. The method that was initially described by Pedersen-Bjergaard et al. (5) required patients to respond to the question, “Can you feel when you are low?” and asked them to select one response from “always,” “sometimes,” “occasionally,” or “never.” Only those who answered “always” were considered to have normal symptomatic awareness of hypoglycemia; the others were designated as having impaired or absent awareness.
The authors state that the method we evaluated in our study was a preliminary dichotomous version and not their current “validated” method, which requires patients to respond to a slightly different question, “Do you have symptoms when you have a hypo?” However, the possible responses and the method of classification of symptomatic awareness were unchanged (6). The “validation” of their current method consisted of examining (via a questionnaire) the state of hypoglycemia awareness of 230 individuals with type 1 diabetes and their history of exposure to mild hypoglycemia during the preceding week and of severe hypoglycemia in the preceding year, with these estimates being made at the start and again at the end of a 1-year period of study. On completion of the study, participants performed an Edinburgh Hypoglycemia Symptom score (7) to document the nature and intensity of their usual hypoglycemia symptoms and were also asked to estimate their usual blood glucose threshold for occurrence of hypoglycemic symptoms. In addition, subjects completed monthly questionnaires documenting rates of mild biochemical hypoglycemia (<3 mmol/l) and severe hypoglycemia. However, “awareness” of hypoglycemia is based on the subjective evaluation of individual patients to perceive the onset of symptoms (8), which the Pedersen-Bjergaard method does not address, unlike the Clarke and Gold methods (via questionnaires and/or hand-held computers).
Irrespective of which version of the Pedersen-Bjergaard et al. method is used, their reported prevalences of impaired awareness of hypoglycemia at 42–45% (5) (depending on whether they were treated with ACE inhibitors) and 57.6% (6) were substantially higher than those reported previously in people with type 1 diabetes at ∼25% (8,9) and by our recent estimates using the other two methods. We therefore maintain that the method proposed by Pedersen-Bjergaard et al. remains unsatisfactory; it overestimates the prevalence of IAH, and it should not be adopted for either research or clinical use.
