185 Use of the hemoglobin A1c test as a screening tool for cystic fibrosis related diabetes

Abstract

Objective To determine the optimal hemoglobin A1c (HgbA1c) level to screen for Cystic Fibrosis Related Diabetes (CFRD) in a population of adults with cystic fibrosis (CF). Methods All oral glucose tolerance test (OGTT) results completed between 2012 and 2014 and HgbA1c tests within 3 months of the OGTT were included. HgbA1c levels were categorized as U5.5%, 5.6–6.4% and ≥6.5%. Chi-square analysis was used to compare HgbA1c categories to the following: 1.presence of CFRD, 2.1 hour OGTT results >199 mg/dL, and 3.1 hour OGTT results >155 mg/dL. Results The number of OGTT tests performed per year is described in Poster Table 1. Descriptive statistics for the sample variables are described in Poster Table 2. Statistical significance was achieved comparing HgbA1c category with 2 hour OGTT results (p = 0.002). Of the patients with an HgbA1c ≤5.5%, 4.8% met criteria for CFRD, as did 16.7% with a HgbA1c between 5.6–6.4% and 60% with a HgbA1c ≥6.5%. Hypoglycemia occurred in 28.6% of patients with a HgbA1c U5.5% having a 2 hour OGTT result 199 mg/dL achieved statistical significance (p = 0.008). Conclusion Based on the results of this observation, using HgbA1c levels as a screening tool may be useful in determining which patients may be appropriate for OGTT testing. Using this method may have the added benefits of decreasing the incidence of hypoglycemia in the population of patients with normal HgbA1c who are most at risk. Using the HgbA1c test may increase the likelihood of patients completing OGTT test and improve utilization of hospital costs and resources.