Background. Poor glycemic control in patients with type 1 diabetes (T1D) is associated with greater social deprivation. However, the evidence is inconsistent in terms of the type of social deprivation (individual-level or area-level) and whether glycemic control changes over time. Here, we investigated the impacts of individual-level and area-level social deprivation on the glycated hemoglobin (HbA1c) trajectory from the time of T1D diagnosis. Materials and Methods. We retrospectively analyzed a cohort of children who were diagnosed with T1D between 2017 and 2020 at Bordeaux University Hospital. Social deprivation was assessed using both parental individual indicator (EPICES score) and ecological indicator (European Deprivation Index (EDI) score). Piecewise linear mixed-effects models were used to estimate the effects of social deprivation on HbA1c trajectory. Results. We included 168 patients. The most-deprived group included 29% and 22% of all patients, as revealed by the respective EPICES and EDI scores. The two indicators were poorly correlated. The short-term decrease in HbA1c level tended to be smaller in the most-deprived patients over the first 4 months after diagnosis than in other patients (slope difference of 2.68% per year compared with the slope among the least-deprived patients, P=0.056). The long-term trajectory was influenced by area-level deprivation (EDI score); the least-deprived patients (quintile 1) exhibited more stable mean HbA1c levels. Conclusions. Social deprivation may partially explain poor glycemic control in some patients; both short-term individual deprivation and long-term area-level deprivation may be involved. Further research is needed to determine how to integrate this information into a therapeutic strategy.< Réduire