Associations of Alternative Markers of Glycemia with Hemoglobin A1c and Fasting Glucose

Abstract

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 A1c (Hb A1c) 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 A1c 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 A1c ≥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 A1c 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 A1c ≥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 A1c and fasting glucose. Future studies should examine these markers in situations in which fasting glucose or Hb A1c measurements are invalid or not available.