Whey proteins are abundant in peptides that possess various biological activities. In order to enhance the biological properties of protein hydrolysates, it is essential to optimize the conditions of the hydrolysis process as much as possible. Firstly, we have determined the optimal conditions for hydrolysis of whey protein concentrate (WPC) by by ltered trypsin-like protease (FTLP) in vitro conditions. Then, the ability of obtained whey protein hydrolysates against inhibit dipeptidyl peptidase-4 (DiPP4) in vitro conditions was examined. The optimum point for WPC hydrolysis by FTLP with the predicted optimal level of Degree of hydrolysis (DH, 42.9 %) was at an E:S ratio of 5:100 (w/w), 8.6 h, and a temperature of 40 °C. The factual DH under ideal conditions was 42.04 %, indicating the e ciency of the selected model (P ≤ 0.05).The ndings indicated that hydrolysates of WPC generated by FTLP, including both the unfractionated section and the fractions obtained via ultra ltration using 10-and 5-kDa cut-off membranes, exhibited anti-diabetic characteristics. However, the fractions exhibited greater inhibitory effects against the DiPP4 enzyme, with IC50 values of 1.98, 1.19, and 0.9 mg/mL for the unfractionated section, 10-kDa fraction, and 5-kDa fraction, respectively. Moreover, the results indicated that probiotic L. plantarum subsp. plantarumPTCC 1896 or its components may provide opportunities for future management of typediabetes by inhibiting DiPP4.