Cardiovascular (CV) diseases are the most frequent type 1 diabetes (T1D) complications. A recent epidemiological study showed that patients with T1D have a two-fold CV mortality risk, even in case of good glycemic control. In addition, it has been shown that patients with T1D with no traditional CV risk factors had about a 80% higher risk of cardiovascular event compared to non-diabetic individuals. This indicates that further modifiable risk factors in relation to CV mortality remain to be identified. One of the candidates that could help to disentangle the factors associated with the increased CV mortality in T1D patients is glycemic variability which could contribute to diabetes complications. Indeed, severe hypoglycaemia, one of the most severe consequence of glycaemic variability, are associated with a higher mortality in patients with type 1 and type 2 diabetes. In order to evaluate the relation between glycemic variability, insulin therapy modalities and CV risk as well as some other questions related to health determinants of T1D, we are building up a large observational, prospective, multi-centric cohort study of patients gathering 15,000 patients with T1D, age above 6 years old, to perform the following: * Collecting clinical information * Evaluating Glycemic variability (assessed by the coefficient of variation of glucose (CV) calculated from automatically downloaded continuous glucose monitoring data (CGM) * Biobanking including plasma, DNA, urine, saliva and hair. * Collecting patients' reported outcomes through auto-questionnaires (online questionnaires). * Doing an active follow-up for a period of 10 years with an intermediate visit every 3 years. * Passive follow-up: link to national Health data system (Système National de Données de Santé, SNDS) in order to exhaustively collect health events as death, CV events and hospitalizations (including severe hypoglycemia).