Obviously, the usual attitude facing an allergy, i. e. exclusion of the allergen, poses problems in face of IA because insulin is often vital for the patient. IA is thus a complex situation in which a rigorous diagnostic procedure to identify the exact allergen is necessary to propose a therapeutic answer; the purpose of the study is 1/ to validate a diagnostic algorithm for patients presenting with possible allergy. 2/ to investigate immunogenetic profiles of patient with insulin allergy 3/ cellular mechanisms of IA.