Associations of Alternative Markers of Glycemia with Hemoglobin A1c 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 R(2) 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 A(1c) 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 A(1c). 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.