Comparison of Hemoglobin A 1c and Fasting Glucose Criteria to Diagnose Diabetes Among People With Metabolic Syndrome and Fasting Glucose Above 100 mg/dL (5.5 mmol/L)

J Clin Hypertens(Greenwich). 2010;12:543–548. © 2010 Wiley Periodicals, Inc. The aim of this study was to compare hemoglobin A 1c (HbA 1c ) and fasting glucose for the diagnosis of diabetes among people with metabolic syndrome and fasting glucose >100 mg/dL (5.5 mmol/L). Consecutive individuals (N=142) with metabolic syndrome and fasting glucose >100 mg/dL (5.5 mmol/L) but without a self‐reported history of diabetes who visited the outpatient lipid and obesity clinic of the University Hospital of Ioannina, Greece from January through September 2009 were included. HbA 1c ≥6.5% and fasting glucose ≥126 mg/dL (7 mmol/L) were used separately to define diabetes. Overall, 29.5% of patients had both HbA 1c ≥6.5% and fasting glucose ≥126 mg/dL (7 mmol/L), 25.3% had HbA 1c ≥6.5% but fasting glucose <126 mg/dL (7 mmol/L), and 9.1% had HbA 1c <6.5% but fasting glucose ≥126 mg/dL (7 mmol/L). A greater proportion of patients reached a diagnosis of diabetes based on the HbA 1c criterion (n=78, 54.9%) compared with the fasting glucose criterion (n=55, 38.7%, P=.000). A large proportion of patients (44.8%) with impaired fasting glucose (fasting glucose 100–125 mg/dL; 5.6–6.9 mmol/L) would be classified as diabetics using the HbA 1c criterion. Implication of the HbA 1c criterion may increase the rate of diabetes diagnosis among people with metabolic syndrome and fasting glucose >100 mg/dL (5.5 mmol/L).