Abstract: 【Abstract】 Objective To investigate clinical characteristics of bullous pemphigoid （BP）developing after the treatment with dipeptidyl peptidase-Ⅳ inhibitors （DPP4i） in patients with diabetes mellitus. Methods A total of 116 inpatients with BP complicated by diabetes mellitus were collected from the Seventh People′s Hospital of Shenyang between January 2014 and December 2020, and divided into 2 groups: DPP4i-BP group treated with DPP4i before the onset of BP, and general BP group receiving no treatment with DPP4i. General clinical data, skin lesion area, laboratory indicators, treatment regimens, and prognosis were analyzed and compared between the above 2 groups, the time interval from the administration of DPP4i to the diagnosis of BP was recorded in the DPP4i-BP group. One-way analysis of variance was used to compare measurement data among multiple groups, two-independent-sample t test was used for comparisons between two groups, and paired t-test for intra-group comparisons before and after treatment; chi-square test was used to compare enumeration data between groups. Results There were 32 patients aged 77.17 ± 15.32 years in the DPP4i-BP group, with a male-to-female ratio being 15∶17; there were 84 patients aged 76.65 ± 19.32 years in the general BP group, with a male-to-female ratio being 43∶41. The time interval from the administration of DPP4i to the diagnosis of BP was 14.61 ± 3.93 months in the DPP4i-BP group. The time interval for vildagliptin was the shortest （5.42 ± 2.84 months）, and there was a significant difference in the time interval among vildagliptin, sitagliptin, linagliptin and saxagliptin （F = 8.93, P < 0.001）. The proportion of patients with severe BP was significantly higher in the DPP4i-BP group （16 cases, 50%） than in the general BP group （25 cases, 29.76%; Z = 2.63, P = 0.008）. There was no significant difference in the positivity rate of anti-BP180 antibody between the two groups （χ2 = 0.03, P = 0.870）. However, the level of anti-BP180 antibody was significantly higher in the DPP4i-BP group than in the general BP group before and after treatment （P = 0.015, < 0.001, respectively）, and the decrease in the level of anti-BP180 antibody was significantly less in the DPP4i-BP group than in the general BP group after treatment（t = 5.11, P < 0.001）. There was no significant difference in the average effective dose of glucocorticoids required to control the disease between the two groups （t = 1.00, P = 0.322）. However, the DPP4i-BP group showed a significant increase in the average time required to control the disease and in the proportion of patients requiring combined treatment with immunosuppressants or other drugs compared with the general BP group （t = 6.72, 10.05, P < 0.001, = 0.002, respectively）. Within 6 months after the start of systemic treatment, the recurrence rate was significantly higher in the general BP group （17 cases, 27.86%） than in the DPP4i-BP group （2 cases, 7.69%; χ2 = 4.35, P = 0.037）; at 6 months, the average dose of glucocorticoids was also significantly higher in the general BP group than in the DPP4i-BP group （t = 7.04, P < 0.001）. Conclusions Among the DPP4i hypoglycemic drugs, vildagliptin was the most common drug administrated by patients before the onset of BP, with the shortest interval from the administration to the onset of BP. DPP4i-BP may be difficult to control at the early stage, but the prognosis is good.

Key words: Pemphigoid, bullous, Dipeptidyl-peptidase Ⅳ inhibitors, Treatment outcome, Drug toxicity, Prognosis