Concordance of Glucose-Based and of HbA1c-Based Diagnoses of Diabetes in Patients with Peripheral Artery Disease—A Comparison between Two Age Groups

Abstract

Concordance between glucose-based and HbA1c-based diagnoses of diabetes differ between populations. Here, we aimed at investigating their concordance in younger and in older patients with peripheral artery disease (PAD). We measured fasting glucose as well as HbA1c and performed 75g oral glucose tolerance tests in 188 consecutive patients, 113 older and 75 younger than 65 years, who had sonographically proven PAD but not previously diagnosed diabetes. Based on glucose values, diabetes was diagnosed with fasting plasma glucose (FPG) ≥126 mg/dl or post-challenge glucose ≥200 mg/dl 2 hours after the oral glucose load; based on HbA1c values diabetes was diagnosed with HbA1c ≥6.5%. Among PAD patients <65 years, 5 had diabetes based on glucose criteria, of whom 3 also had diabetes according to the HbA1c criterion, and 70 did not have diabetes according to glucose criteria, of whom 67 also did not have diabetes using HbA1c criteria; among those ≥65 years, 19 had diabetes based on glucose criteria, of whom 10 also had diabetes according to the HbA1c criterion and 94 did not have diabetes based on glucose criteria, of whom 93 also did not have diabetes according to HbA1c criteria. Concordance of glucose and HbA1c criteria was similar in younger and older PAD patients (93.3% and 91.2%; p=0.589). Applying glucose criteria as a standard, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the HbA1c criterion for PAD patients <65 years were 60.0%, 95.7%, 50.0%, and 97.1%, and for those ≥65 years 52.6%, 98.9%, 90.9%, and 91.2%. We conclude that the concordance of glucose and HbA1c criteria among patients with PAD is high and is similar in older and younger subjects. However, for both age groups the sensitivity of the HbA1c criterion is poor in this patient population. Disclosure C.H. Saely: None. A. Vonbank: None. C. Heinzle: None. D. Zanolin: None. B. Larcher: None. A. Mader: None. A. Leiherer: None. A. Muendlein: None. H. Drexel: None.