Establishment of a reference interval for glycated albumin based on medical check-up data from multiple medical institutions.

Objectives: Data were collected to establish a reference interval for glycated albumin (GA), as well as to calculate a cutoff value for diagnosing diabetes mellitus and the GA level corresponding to a 75-g oral glucose tolerance test (OGTT) 2 h plasma glucose (2h-PG) level of 200 mg/dL.Methods: This study involved 1,843 subjects who were undergoing medical check-ups at several medical institutions and whose HbA1c and GA levels had been measured by OGTT.Results: The GA reference interval that was calculated based on the data obtained from study subjects with normal glucose tolerance was 12.1-17.1%. Using standardized major axis regression, the levels that corresponded to an OGTT 2h-PG level of 11.1 mmol/L were a GA level of 17.5% and an HbA1c level of 47.5 mmol/mol. A receiver-operating characteristic curve analysis was used to calculate the points at which sensitivity and specificity matched as the cutoff values, and the results yielded a GA level of 15.0% (sensitivity 69.3%).Conclusions: The GA reference interval was calculated to be 12.1-17.1%. We propose a GA level of 17.4% as a cutoff value to diagnose diabetes mellitus and a GA level of 15.0% as a screening cutoff value for diabetes mellitus, taking previous reports into account.