Early Detection of Type 1 Diabetes

T1D is an autoimmune disease characterized by the presence of autoantibodies usually assayed separately on venous blood. The use of a combined test on capillary blood using a blotting paper would facilitate the immunological presymptomatic T1D screening in routine clinical practice as it is easy to perform and can be performed at home by families. However the use of a combined test on blotting paper must be validated before it is used in routine clinical practice for preclinical T1D screening purpose at large scale, starting with pediatric first degree relatives of T1D patients: this is the aim of this study, where we will assess the concordance of 3 autoantibodies rates (anti-GAD65, anti-IA2 and anti-ZnT8) between a combined assay on capillary blotting paper and the individual measurement of these 3 autoantibodies in venous blood at the time of discovery of type 1 diabetes (stage 3). The combined immunological test used in this study has already been validated (test available on the market: (Biosynex - product code: RL 3ZGl/96D); However, it has never been used on capillary blood eluate from blotting paper. The blotting paper to be used is also marketed and used in current clinical practice for newborn screening (test WHATMAN® + SAVER CARDS 903x100 - ref: 034955). Of note: this ELISA 3 screen test does not include IAA. In clinical practice, for stage 3 patients, IAA (from venous samples) is systematically tested for children \< 6-year-old. For older children they are tested only if the other 3 autoantibodies are negative. (IAA are found more commonly in young children and mainly below 4 years old and mark a higher risk of progression at a very young age. A single IAA positivity in children can therefore justify a closer surveillance in the short term). HCL choose to validate the combined assay (3 Screen + blotting paper) in symptomatic children with suspicion of type 1 diabetes at stage 3, to be further used for pre-clinical T1D screening activities across Auve