Potential participants will have a screening visit to review overall health, measure diabetes T1D-associated autoantibodies and perform a MMTT, which will also serve as the baseline MMTT. Eligible subjects will be invited to participate in the intervention trial and randomized to treatment with Proleukin® or placebo. Fifty-four patients will be enrolled, aged 12-21 years, both genders, and randomized to treatment or placebo in a 2:1 ratio. Participation for each subject will last approximately 2 years. The 18 patients randomized to the control arm will receive placebo for two years. At the end of the first year, the 36 patients randomized to the treatment arm will be randomized 1:1 to continued treatment or placebo. Thus, among the 36 patients who received treatment during the first year, 18 patients will continue therapy and 18 patients will switch to placebo until the end of the study. This study design allows examining safety and efficacy at one year (primary outcome), and further evaluates these parameters after the therapy has stopped or it is continued up to the end of 2 years (secondary outcome).