Phenotypic and Genotypic Characterization of New-onset Type I Diabetes

Inclusion Criteria: 1. Type 1 diabetes de novo according to American Diabetes Association criteria: 1. Polyuria, polydipsia, weight loss ± ketoacidosis 2. Fasting blood glucose ≥126 mg/dL AND/OR blood glucose ≥200 mg/dL at the 120th minute of an Oral Glucose Tolerance Test (OGTT) AND/OR HbA1c ≥6.5% AND/OR a patient with symptoms of hyperglycemia/hyperglycemic crisis (see 8. a. 2.) with random blood glucose ≥200 mg/dL. 3. Presence in the serum of one or more anti-islet autoantibodies (anti-insulin, anti-IA2, anti-GAD65, anti-ZnT8) 2. Age between 6 months and 18 years. 3. Male or female. 4. Positive for one or more autoantibodies typically associated with Type 1 Diabetes (TD1). 5. Free written and oral consent. Exclusion Criteria: 1. Children under 6 months of age. 2. Treatment that interferes with insulin secretion and insulin sensitivity (e. g. sulfonylureas, diazoxide, somatostatin, methylxanthine derivatives, corticosteroids, biguanide, incretins). 3. Presence of celiac disease (diagnosis based on pathological duodenal biopsy), recently diagnosed (within 1 month), at the time of inclusion. 4. Autoimmune/auto-inflammatory disease (other than type 1 diabetes) or active malignant disease present at inclusion. 5. Obesity defined by a Body Mass Index (BMI) with a z-score \>+3 Standard Deviation. 6. Hepatic, renal or adrenal insufficiency. 7. History of spinal cord allograft. 8. History of post-hemolytic-uremic diabetes. 9. Absence of anti-pancreatic islet auto-antibodies. 10. Dysmorphic with suspicion of underlying genetic syndrome. 11. Participation in another study within the previous 3 months, with administration of blood derivatives or potentially immunomodulating treatments.