Okubo et al. demonstrated in their study that T1D patients with tight glucose control (based on the HbA1c level) showed higher percentage of activated Tregs (CD4+CD25+FoxP3+CD45RA+) in peripheral blood and lower percentage of resting Tregs (CD4+CD25+FoxP3+CD45RO+). Here, FOXP3 is linked to type 1 diabetes mellitus.