DPP4 and COVID-19: Subgroup analysis indicated a prevalence of 9.43% (95% CI − 13.86 to 32.73%; n = 10 studies) of COVID-19 among the patients with CD26–28,34,35,45,46,73,76,84 and 8.58% (95% CI − 8.22 to 25.38; n = 10 studies) among those patients with UC27,28,34,35,45,46,55,73,76,84.