| Coding | Source literature | Fasting C-peptide (ng/ml) | Reference range of fasting C-peptide (ng/ml) | Positive antibody |
| 1 | Mellati et al., 2015 [21] | <0.1 | 1.0~71 | GAD+ |
| 2 | Hughes et al., 2015 [22] | <0.1 | 1.1~4.4 | GAD+ |
| 3 | Hughes et al., 2015 [22] | 1.3 | 1.1~4.4 | GAD+, ICA+a, IAA+ |
| 4 | Hughes et al., 2015 [22] | <0.1 | 1.1~4.4 | GAD+ |
| 5 | Hansen et al., 2016 [23] | 2.4 | 1.1~4.4 | GAD+ |
| 6 | Chae et al., 2017 [24] | 0.81 | 0.9~3.85 | GAD+, IAA+ |
| 7 | Lowe et al., 2016 [25] | <0.1 | Unknown | GAD+ |
| 8 | Hofmann et al., 2016 [26] | Low | Unknown | GAD+ |
| 9 | Hofmann et al., 2016 [26] | Low | Unknown | GAD+ |
| 10 | Alhusseini and Samantray, 2017 [27] | Undetectable | Unknown | GAD+, IAA+ |
| 11 | Godwin et al., 2017 [28] | <0.1 | 0.8~3.85 | GAD+ |
| 12 | Usui et al., 2017 [17] | <0.03 | > 0.03 | GAD+ |
| 13 | Alzenaidi et al., 2017 [29] | 0.2 | 0.9~5.5 | GAD+ |
| 14 | Leonardi et al., 2017 [30] | 0.3 | 1.1~4.4 | GAD+ |
| 15 | Gauci et al., 2017 [31] | 0 | 0.5 | GAD+, ZnT8A+b |
| 16 | Kapke et al., 2017 [32] | 0.32 | 1.1~4.4 | GAD+ |
| 17 | Kapke et al., 2017 [32] | 0.02 | 1.1~4.4 | GAD+ |
| 18 | Araújo, et al. 2017 [33] | 0.06 | <0.1 | GAD+ |
| 19 | Clotman et al., 2018 [6] | 0.3 | 0.8~3.1 | GAD+, ICA+ |
| 20 | Fillette et al., 2019 [34] | 0.02 | 0.29~0.99 | GAD+ |
| 21 | Code 2 | 0.53 | 1.1~4.4 | IAA+ |
| 22 | Code 3 | 0.19 | 1.1~4.4 | GADA+ |