Inclusion Criteria:  Age of the subject between 6 and 45 years Subject (or legal guardian in the case of a minor) is able to provide informed consent If a first degree relative of the proband with T1D must be between 6 and 45 years old (brother, sister, parent, child) If a relative of the proband with T1D is second degree, he must be between 6 and 20 years old (nephew, uncle, aunt, grandfather, grandmother, cousin) Presence of at least two autoantibodies associated with diabetes Impaired glucose tolerance on the OGTT test (fasting glucose greater than 110 mg/dl but less than 126 mg/dl or 2-hour glucose greater than or equal to 140 mg/dl but less than 200 mg/dl or 'OGTT at 30', 60 ', 90' greater than or equal to 200 mg/dl) If the subject is a female with reproductive potential, she must have a negative pregnancy test at the enrollment visit and must agree not to seek pregnancy for at least one year from randomization If the subject is male, he must agree not to seek pregnancies with any partner for at least one year from the randomization The subject must agree to renounce other types of trials during this study Weight at the time of recruitment of at least 26 kg It must be favorable and clinically acceptable to postpone vaccinations with live and attenuated agents for at least one year after treatment  Exclusion Criteria:  Type 1 Diabetes Mellitus previously diagnosed or diagnosed during screening investigations Serological evidence of current or past HIV, Hepatitis C, Hepatitis B Changes in blood counts, INR or liver enzymes Being pregnant or breastfeeding Evidence of pancreatic changes in the laboratory Having undergone a previous experimental treatment for Type 1 Diabetes Mellitus Chronic Renal Failure stage IIIa onwards (eGFR <45 ml / min / 1.7 m2) History of previous pancreatitis Lymphopenia (<1000 lymphocytes / µL) Neutropenia (<1500 PMN / µL) Thrombocytopenia (<150,000 platelets / µL) Anemia (Hgb <10 grams / deciliter [g / dL]) AST or ALT> 1.5 x ULN Total bilirubin> 1.5 x upper limit of normal (ULN) with the exception of subjects diagnosed with Gilbert's syndrome who may be eligible provided they have no other cause leading to hyperbilirubinemia INR> 0.1 above the upper limit of the norm at the laboratory of the participating center Alterations of Amylase and Lipase due to the pancreas Chronic active infection other than localized skin infections A positive PPD test Vaccination with a live virus within 8 weeks of randomization Vaccination with a killed virus within 4 weeks of randomization Laboratory or clinical evidence of acute EBV or CMV infection Serological evidence of current or past HIV, hepatitis B or hepatitis C infection Being currently pregnant or breastfeeding, or planning to become pregnant Chronic use of steroids or other immunosuppressive agents A history of asthma or atopic disease that requires chronic treatment Untreated hypothyroidism or active Graves' disease at randomization Current use of non-insulin drugs that affect glycemic control Previous OKT®3 or other anti-CD3 treatment Administration of a monoclonal antibody within the year prior to randomization Participation in any type of clinical trial of therapeutic drugs or vaccines in the 12 weeks prior to randomization Any conditions that, in the opinion of the investigator, could interfere with the conduct of the study or with the safety of the subject.