CD4 and diabetes mellitus: We concluded from these results that Foxp3 expression by CD4+CD25+ regulatory T cells is lower in diabetes-prone (NOD) than diabetes-resistant (B6) mice, and the lower expression of Foxp3 by NOD CD4+CD25+ cells is unlikely to be due to exposure to high glucose levels, although we cannot rule out a possible role for other metabolites in NOD mice.