Glycated albumin to glycated hemoglobin ratio reflects postprandial glucose excursion and relates to beta cell function in both type 1 and type 2 diabetes

The glycated albumin (GA) to HbA1c ratio (GA/HbA1c ratio) has been proposed as a marker of postprandial glucose excursion. The aim of this study was to explore the correlation between the GA/HbA1c ratio and beta cell function. Three hundred sixteen subjects with type 2 diabetes who had been admitted to our hospital were examined. Blood samples were obtained after fasting and 2 h after breakfast. Beta cell function was assessed by the serum C-peptide immunoreactivity (CPR) to plasma glucose ratio. Similarly, the correlation between the GA/HbA1c ratio and beta cell function was also estimated in 61 subjects with type 1 diabetes. As a result, the GA/HbA1c ratio was significantly correlated with the postprandial plasma glucose (r = 0.274, p < 0.001) and postprandial increment of plasma glucose (r = 0.269, p < 0.001), but not fasting plasma glucose level (r = 0.081, p = 0.15). Among HbA1c, GA and GA/HbA1c ratio, the GA/HbA1c ratio showed the highest correlation with beta cell function in subjects with type 2 diabetes (r = −0.455, p < 0.001). A robust association between beta cell function and the GA/HbA1c ratio was shown by multiple regression analysis adjusting for confounders. Similar correlations were also observed in subjects with type 1 diabetes. In conclusion, we confirmed a negative association between beta cell function and the GA/HbA1c ratio, a marker of postprandial glucose excursion, in this study using a relatively large sample size. These results indicate that beta cell dysfunction is associated with larger glucose excursions in subjects with both type 1 and type 2 diabetes.