Anti-BP180 NC7-Col4 autoantibodies were present in patients with DM + DPP4i who do not have BP symptoms, which also raises the question of whether patients with DM + DPP4i who have anti-BP180 NC7-Col4 autoantibodies might have a higher risk of BP development than those without anti-BP180 NC7-Col4 autoantibodies. This evidence concerns the gene COL17A1 and diabetes mellitus.