The clinical investigator(s) will evaluate beta-cell function by examining C-peptide response during a MMTT, and using glucose and C-peptide data obtained during the MMTTs investigator(s) will determine beta-cell sensitivity to glucose, insulin sensitivity, and insulin secretion using the Mari model (99). It is documented that ß-cells in T1D are "blind" to glucose, by showing reduced ß-cell sensitivity to glucose using the Mari model in relatives at risk of T1D (100). The extent, to which this may account for reduced ß-cell function, and whether this is to any degree reversible, is unknown. Thus, clinical investigator(s) will characterize ß-cell function in response to low-dose IL-2 by measuring insulin secretion during a 4-hour MMTT, and using the Mari model to calculate ß-cell sensitivity to glucose and insulin sensitivity/resistance.