10 T1DM patients and 10 healthy age gender and BMI matched control subjects will be recruited. All subjects will be studied on 2 separate occasions at 1-2 weeks intervals. Both in patients and in controls, study 1 will be identical to protocol 1 (i.e. an insulin clamp and an IVGTT, respectively). In study 2 all subjects will be admitted to the Clinical Research Center (CRC) on the morning of the study (07:00 AM) and will stay there for its entire duration (24 hours). Subjects will be allowed to move freely within the CRC, but they will not be engaged in any physical exercise. Patients will continue their usual insulin therapy, including meal insulin dose calculation and injection, throughout the study. At 08:00 AM, 13:00 and 19:00 subjects will ingest three mixed meals (200 kcal/m-2 of Body Surface Area (BSA), 400 kcal/m-2 BSA and 400 kcal/m-2 BSA, respectively; diet composition: 54% carbohydrate, 28% lipid, 18% protein). In 6 patients and in 6 controls, the 13:00 meal will be Indian corn polenta plus seasoned Italian DOP parmesan cheese. In the other 6 patients and 6 controls, the 19:00 meal will be Indian corn polenta plus seasoned Italian DOP parmesan cheese. Timed blood samples (n=62) will be collected. Plasma glucose, insulin, glucagon and C-peptide (the latter one only in control subjects) will be measured at all time points. At a lower time frequency, triglycerides, non-esterified fatty acids (NEFA), amino acids, active GLP1 and total GIP will also be measured. In those subjects ingesting the polenta meal at 13:00, the 13C/12C-glucose ratio will be measured from 12:00 until 24:00. In those subjects ingesting the polenta meal at 19:00, the 13C/12C-glucose ratio will be measured from 18:00 until 07:00 the morning after. Subcutaneous glucose will be monitored by CGM only in patients. The polenta meal will be used only in one meal per day to avoid loss of interpretability of 13C/12C-glucose ratio data, owing to ongoing glucose carbon recirculation/recycling through glycogen/gluconeogenesis. The behaviour of the glucose/insulin system at breakfast time is already explored in Protocol 1. Results will be layered and analyzed as described in Protocol 1.