After 6 days of stimulation and 15μM Pep3, percentages of type 1 diabetes patients’ CD8+ Treg were increased, total CD8+ Teff were diminished, CD8+ Treg/Teff ratio was increased as were the percentages of activated CD8+ Teff within the total CD8+ Teff. Here, VPS18 is linked to type 1 diabetes mellitus.