Inverse Association between Glycated Albumin and Insulin Secretory Function May Explain Higher Levels of Glycated Albumin in Subjects with Longer Duration of Diabetes

Background: Glycated albumin (GA) has been increasingly used as a reliable index for short-term glycemic monitoring, and is inversely associated with b-cell function. Because the pathophysiologic nature of type 2 diabetes (T2D) is characterized by progressive decline in insulin secretion, the aim was to determine whether GA levels were affected by diabetes duration in subjects with T2D. Methods: To minimize the effect of glucose variability on GA, subjects with stably maintained HbA1c levels of,0.5% fluctuation across 6 months of measurements were included. Patients with newly diagnosed T2D (n = 1059) and with duration.1 year (n = 781) were recruited and categorized as New-T2D and Old-T2D, respectively. Biochemical, glycemic, and C-peptide parameters were measured. Results: GA levels were significantly elevated in HbA1c-matched Old-T2D subjects compared to New-T2D subjects. Duration of diabetes was positively correlated with GA, whereas a negative relationship was found with C-peptide increment (DC-peptide). Among insulin secretory indices, dynamic parameters such as DC-peptide were inversely related to GA (r=20.42, p,0.001). Multiple linear regression analyses showed that duration of diabetes was associated with GA (standardized b coefficient [STDb] = 0.05, p,0.001), but not with HbA1c (STDb = 0.04, p,0.095). This association disappeared after additional adjustment with DC-peptide (STDb = 0.02, p = 0.372), suggesting that b-cell function might be a linking factor of clos