The impact of acute illness on HbA1c determination of undiagnosed diabetes

Objective To improve diabetes screening efforts, the American Diabetes Association now recommends haemoglobin A1c (HbA1c) as a diagnostic test, increasing access to patients found in acute care environments. However, the influence of acute illness and care on HbA1c levels has not been well studied. To address this, we evaluated for intra-patient differences in HbA1c assessed in the emergency department (ED) and after recovery from the acute illness. Methods Adult patients with no known history of diabetes were tested for HbA1c during an ED and scheduled follow-up visit. HbA1c differences between the two visits were compared using limits of agreement with 95% confidence intervals. The frequency of individuals who changed diagnostic categories (using =6.5% to classify newly diagnosed diabetes) from ED to follow-up was determined. Results A total of 589 patients were included with a mean age of 50?years, and 57/589 (9.7%) had an ED HbA1c?=?6.5% with the average follow-up visit 45?days after the ED visit. The mean ED HbA1c was 5.67% (+/-0.86), and the follow-up HbA1c was 5.65% (+/-0.89), (difference -0.0129%, 95% limits of agreement -0.740, 0.714). The ED and follow-up HbA1c was highly correlated (r(2)?=?0.829). Although on follow-up almost all patients were classified in the same diagnostic category as in the ED, 17 patients had an HbA1c?=?6.5% in the ED and an HbA1c?<?6.5%. On follow-up most patients (14/17) still fell in an abnormal range (6.06.5%). Conclusion The HbA1c value is not substantially affected by acute illness and is feasible as a screening assay for diabetes in the acute care setting such as an ED. Copyright (C) 2012 John Wiley & Sons, Ltd.