INS and diabetes mellitus: Participants in the preserved–C-peptide group were younger [48 (IQR, 34–61) vs. 54 (IQR, 38–64) years, P = 0.002], had a shorter diabetes duration [4.0 (IQR, 0.7–12.0) vs. 15.0 (IQR, 7.0–32.0) years, P<0.001], and had a lower insulin dose [29.4 (IQR, 20.0–40.0) vs. 36.0 (IQR, 28.3–46.0) U/d, P <0.001] compared with those in the low–C-peptide group.