RecruitingDiagnostic testHome-based Oral Glucose Tolerance Test for Type 1 Diabetes ScreeningThis study aims at quantifying the accuracy of a self-administered fingerstick based glucose tolerance test (GTT@Home) respect to the gold-standard in-clinic venous plasma measures during the oral glucose tolerance test (OGTT) across a wide range of glycemic values in people at risk for clinical type 1 diabetes (T1D) (carriers of at least one islet autoantibody) or with new onset Stage 3 T1D within 100 days from the diagnosis.