Associations of alternative markers of glycemia with hemoglobin A _1c and fasting glucose

BACKGROUND: 1,5-Anhydroglucitol (1,5-AG), fructosamine, and glycated albumin are of increasing interest as alternative measures of hyperglycemia. We characterize the associations of these nontraditional glycemic markers with hemoglobin A_1c (Hb A_1c) and fasting glucose and assess their ability to identify people with diabetes. METHODS: We conducted a cross-sectional comparison of 1,5-AG, fructosamine, and glycated albumin with Hb A_1c and fasting glucose measurements in 1719 participants from the Atherosclerosis Risk in Communities Study. We evaluated nonlinear relationships using R² and F-statistics. Performance for identification of cases of diabetes was determined using the area under the curve (AUC). Diabetes was defined by Hb A_1c ≥6.5%, fasting glucose ≥126 mg/dL (≥6.99 mmol/L), and/or a self-reported history of diagnosed diabetes. RESULTS: Median values of Hb A_1c and fasting glucose were 5.8% and 109 mg/dL (6.05 mmol/L), respectively; 17.3% of the study population had diagnosed diabetes. Glycated albumin, fructosamine, and 1,5-AG were more strongly correlated with Hb A1c compared with fasting glucose (all P values <0.05). Nonlinear models provided the best fit for describing the relationships of the alternative markers to Hb A1c. When diabetes was defined by an Hb A_1c ≥6.5%, fructosamine (AUC 0.83; 95% CI, 0.79-0.87) and glycated albumin (AUC 0.87; 95% CI, 0.83-0.90) performed comparably to fasting glucose (AUC 0.83; 95% CI, 0.79-0.87), while 1,5-AG performed worse (AUC 0.74; 95% CI, 0.69-0.78) for identifying cases of undiagnosed diabetes. CONCLUSIONS: Fructosamine and glycated albumin may be useful adjuncts to Hb A_1c and fasting glucose. Future studies should examine these markers in situations in which fasting glucose or Hb A_1c measurements are invalid or not available.