There were no significant differences between the genders, intake periods of DPP-4i, nor of hemoglobin A1c levels, the anti-full-length BP180 IgG-positive cases tended to be significantly older than anti-full-length BP180 IgG-negative cases (median 74 vs. 69, p = 0.025) in the DPP-4i (+) T2DM cases. Here, COL17A1 is linked to type 2 diabetes mellitus.