In our hands, injection of Treg-targeting anti-CD25 monoclonal antibody (mAb) into prediabetic NOD mice at the age of 10–12 weeks but also injection of anti-CD25 or anti-CD8 mAbs into early diabetic NOD mice (with blood glucose levels between 250 and 350 mg/dl) was inefficient and attenuated diabetes progression only in about 15%–20% of mice (data not shown). This evidence concerns the gene CD8A and diabetes mellitus.