In the present study, we document, for the first time, that WJ-MSC transplantation decreased the level of HbA1c; increased the level of fasting C-peptide; decreased the fasting glucose level, 2 h postprandial blood glucose level, insulin requirement and oral hypoglycemic drugs; and reduced the systemic inflammation and T lymphocyte counts in patients with T2DM. Here, INS is linked to type 2 diabetes mellitus.