Difference in DPP-4 activity exists between persons with T1, T2 diabetes and LADA. Dipeptidyl peptidase-4 activity is highest in persons with latent autoimmune diabetes in adults. Dipeptidyl peptidase-4 activity correlates with glutamic acid autoantibody. Dipeptidyl peptidase-4 inhibitors might be considered in treatment of autoimmune diabetes.