Testing for HbA1c, in addition to the oral glucose tolerance test, in screening for abnormal glucose regulation helps to reveal patients with early β-cell function impairment

<jats:title>Abstract</jats:title>
<jats:sec id="j_cclm-2017-0846_s_999">
<jats:title id="d8889357e14615">Background:</jats:title>
<jats:p>The oral glucose tolerance test (OGTT) is recommended to screen for diabetes in patients with coronary artery disease. We hypothesized that testing for glycated hemoglobin (HbA<jats:sub>1c</jats:sub>), in addition to the OGTT, in screening for abnormal glucose regulation may help to reveal patients with β-cell function impairment.</jats:p></jats:sec>
<jats:sec id="j_cclm-2017-0846_s_998">
<jats:title id="d8889357e14626">Methods:</jats:title>
<jats:p>Patients with no history of diabetes who were admitted for coronary angiography were recruited to undergo an OGTT and HbA<jats:sub>1c</jats:sub> test 2–4 weeks after hospital discharge. β-cell function and insulin resistance were assessed using the homeostasis model assessment (HOMA-β and HOMA-IR, respectively). For patients with normal glucose tolerance (NGT) based on the OGTT, we compared HOMA-β between two subgroups of patients using an HbA<jats:sub>1c</jats:sub> cutoff of 39 mmol/mol or 42 mmol/mol. For patients with prediabetes based on an OGTT, we compared the HOMA-β between two subgroups of patients using an HbA<jats:sub>1c</jats:sub> cutoff of 48 mmol/mol.</jats:p></jats:sec>
<jats:sec id="j_cclm-2017-0846_s_997">
<jats:title id="d8889357e14643">Results:</jats:title>
<jats:p>A total of 1044 patients were analyzed. In patients with NGT by OGTT (n=432), those with an HbA<jats:sub>1c</jats:sub> ≥42 mmol/mol had a lower HOMA-β compared to those with an HbA<jats:sub>1c</jats:sub> <42 mmol/mol (107±82 vs. 132±96, p=0.018). In patients with prediabetes by OGTT (n=423), those with an HbA<jats:sub>1c</jats:sub> ≥48 mmol/mol had a lower HOMA-β compared to those with an HbA<jats:sub>1c</jats:sub> <48 mmol/mol (91±52 vs. 120±88, p=0.003). No significant between-group difference in HOMA-IR was noted.</jats:p></jats:sec>
<jats:sec id="j_cclm-2017-0846_s_996">
<jats:title id="d8889357e14663">Conclusions:</jats:title>
<jats:p>The use of HbA<jats:sub>1c</jats:sub> in addition to the OGTT in screening for abnormal glucose regulation helped to reveal patients with early β-cell function impairment.</jats:p></jats:sec>