GCG and type 2 diabetes mellitus: The 3β-HSD concentration in the early-onset T2DM group was lower than that in the late-onset T2DM group (11.07 ± 3.05 vs. 12.40 ± 2.72 pg/mL, p = 0.048) and was positively correlated with fasting C-peptide, while negatively correlated with HbA1c and fasting glucagon (p all < 0.05).