Control (n=51) | T1DM (n=48) | T1DM with NP-DPN (n=67) | T1DM with P-DPN (n=50) | P value | P value adj. | P value (NP-DPN vs P-DPN) | P value adj. (NP-DPN vs P-DPN) | |

IENFD (abnormal) | 6 (12.0%) | 16 (34.0%) | 54 (81.8%) | 38 (84.4%) | 0.000* | 0.000* | 0.801 | 0.733 |

IENFD, ankle (fibers/mm) | 4.9 (4.0; 6.4) | 3.9 (1.7; 4.7) | 1.4 (0.4; 2.2) | 0.6 (0.2; 2.2) | 0.000* | 0.000* | 0.133 | 0.107 |

DPNCheck (abnormal) | 6 (12.0%) | 6 (12.8%) | 55 (84.6%) | 38 (80.9%) | 0.000* | 0.000* | 0.619 | 0.882 |

DPNCheck, amplitude (μV) | 8.0 (6.0; 12.0) | 9.0 (6.0; 13.0) | 3.0 (2.0; 5.0) | 3.0 (2.0; 5.0) | 0.000* | 0.000* | 0.510 | 0.685 |

DPNCheck, conduction velocity (m/s) | 55.0 (51.0; 61.0) | 50.0 (45.0; 54.0) | 40.0 (25.0; 46.0) | 38.0 (28.0; 45.5) | 0.000* | 0.000* | 0.848 | 0.477 |

Categorical variables: presented as number of

*x*and its percentage within each group. Continuous variables: presented as median with the 25th and 75th quartile within each group. All-group comparisons (p value) were carried out using Fisher’s exact test (categorical variables) and Kruskal-Wallis H test (continuous variables). Two-group comparisons between T1DM with NP-DPN and T1DM with P-DPN (p value (NP-DPN vs P-DPN)) were carried out using Fisher’s exact test (categorical variables) and Mann-Whitney U test (continuous variables). Adjustments for sex, age, HbA1c, and diabetes duration (p value adj.) were calculated using a logistic regression model (categorical variables) and a linear regression model (continuous variables).*P<0.0

adj., adjusted; HbA1c, hemoglobin A1c; IENFD, intra-epidermal nerve fiber density; NP-DPN, non-painful diabetic polyneuropathy; P-DPN, painful diabetic polyneuropathy; T1DM, type 1 diabetes mellitus.