INS and type 2 diabetes mellitus: T1D patients, on the other hand, had significantly lower levels of fasting insulin (2.90 ± 1.63 vs. 28.73 ± 27.25 μU/mL, p < 0.001) and C-peptide levels (0.42 ± 0.27 vs. 3.17 ± 2.16 ng/mL, p < 0.001) compared to those with T2D.