This study investigates the association between socioeconomic status (SES) and glycemic control in individuals with type 1 diabetes (T1D) using flash glucose monitoring (FGM) devices within a public health system where these technologies are freely available and utilized according to recommended guidelines. The study included 1060 adults with T1D from three Spanish university hospitals, with a mean follow-up of 2.3 years. SES was assessed using the Spanish Deprivation Index and average annual net income per person. Glycemic data were collected over a 14-day period, including baseline and follow-up HbA1c levels and FGM-derived glucose metrics. Chronic micro and macrovascular complications were documented. Regression models, adjusted for clinical variables, were used to determine the impact of SES on optimal sensor control (time in range ≥70% with time below range <4%) and disease complications. Key findings include: - Individuals in the highest SES quartile had higher mean time in range (TIR) and percentage of optimal control (27.9%) compared to those in the lowest quartile (12.1%). - Regression models showed a higher risk of suboptimal control (OR 2.27, p < 0.001) and ischemic heart disease and/or stroke (OR 3.59, p = 0.005) in the lowest SES quartile. - No significant association was observed between SES and the risk of diabetic nephropathy and retinopathy. - FGM improved HbA1c levels across all SES quartiles, but significant disparities in HbA1c between SES groups were reduced after FGM technology use. The study concludes that SES plays a significant role in glycemic control and complications in individuals with T1D, extending beyond access to technology and its proper utilization. The free utilization of FGM technology helps alleviate the impact of social inequalities on glycemic control.This study investigates the association between socioeconomic status (SES) and glycemic control in individuals with type 1 diabetes (T1D) using flash glucose monitoring (FGM) devices within a public health system where these technologies are freely available and utilized according to recommended guidelines. The study included 1060 adults with T1D from three Spanish university hospitals, with a mean follow-up of 2.3 years. SES was assessed using the Spanish Deprivation Index and average annual net income per person. Glycemic data were collected over a 14-day period, including baseline and follow-up HbA1c levels and FGM-derived glucose metrics. Chronic micro and macrovascular complications were documented. Regression models, adjusted for clinical variables, were used to determine the impact of SES on optimal sensor control (time in range ≥70% with time below range <4%) and disease complications. Key findings include: - Individuals in the highest SES quartile had higher mean time in range (TIR) and percentage of optimal control (27.9%) compared to those in the lowest quartile (12.1%). - Regression models showed a higher risk of suboptimal control (OR 2.27, p < 0.001) and ischemic heart disease and/or stroke (OR 3.59, p = 0.005) in the lowest SES quartile. - No significant association was observed between SES and the risk of diabetic nephropathy and retinopathy. - FGM improved HbA1c levels across all SES quartiles, but significant disparities in HbA1c between SES groups were reduced after FGM technology use. The study concludes that SES plays a significant role in glycemic control and complications in individuals with T1D, extending beyond access to technology and its proper utilization. The free utilization of FGM technology helps alleviate the impact of social inequalities on glycemic control.