[Alopecia areata universalis under treatment with sitagliptin : Possible immunological effect of dipeptidyl peptidase-4 inhibitors?].

A 64-year old man developed alopecia universalis after one month of treatment with metformin and sitagliptin, a dipeptidyl peptidase‑4 (DPP-4) inhibitor. Diabetes treatment was changed to another genericum of sitagliptin and dapagliflozin. Following our recommendation, sitagliptin was interrupted and monotherapy with dapagliflozin was continued. After 6 weeks, sitagliptin was reassumed due to unsatisfactory diabetes control. Alopecia did not improve. We suspect a connection between DPP‑4 inhibition and development of alopecia due to its immunological potential. We assume that the treatment interruption might have been too short to induce regrowth of hair. DPP‑4 may result in both inhibition and activation of the immune system.