The invention relates to a method for assessing the efficacy of an immunotherapy comprising administration of GAD to a patient, comprising the following steps: measuring at least one of GADA IgG subclass distribution； GADA levels； distribution of cytokines secreted from lymphocytes； and lymphocyte proliferation in presence of GAD or CD3/CD28 beads； in a first blood, plasma or serum sample obtained from said patient at a first point in time and in a second blood, plasma or serum sample obtained from said patient at a later point in time； and comparing the so obtained measurements. The invention also relates to novel administration regimens of GAD in treatment or prevention of type 1 diabetes, that may include administration by injection into a lymph node, oral administration of vitamin D and/or an assessment of efficacy according to the above methodology followed by an adjustment of dosage and/or administration route based on said assessment.
