INS and diabetes mellitus: The glucose-related variables such as FPG and HbA1c, which are widely used for the diagnosis of diabetes, were highly correlated with the other glucose-related variables such as GA and 1,5-AG (r=0.778 and −0.629 for FPG, r=0.761 and −0.758 for HbA1c, respectively) and showed low correlations with the insulin-related variables such as C-peptide, insulin and HOMA-IR.