Comparison of hemoglobin A1c and fasting glucose criteria to diagnose diabetes among people with metabolic syndrome and fasting glucose above 100 mg/dL (5.5 mmol/L).

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)> or =6.5% and fasting glucose > or =126 mg/dL (7 mmol/L) were used separately to define diabetes. Overall, 29.5% of patients had both HbA(1c)> or =6.5% and fasting glucose > or =126 mg/dL (7 mmol/L), 25.3% had HbA(1c)> or =6.5% but fasting glucose <126 mg/dL (7 mmol/L), and 9.1% had HbA(1c) <6.5% but fasting glucose > or =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).