Background: The unique confining experience caused by the COVID-19 changed the normality and daily routine of most of the global population, including people with diabetes, especially their routines of glycemic control, self-care, self-efficacy, and knowledge. Besides that, in handling insulin for diabetes and practices of users under the insulin pump system before and after the COVID-19 pandemic is worrying problem. Aims: The current study analyzed the glycemic control, self-care, self-efficacy, and knowledge of people with type 1 diabetes using an insulin pump system before and after the COVID-19 pandemic. Materials and Methods: Quantitative, descriptive, and longitudinal study, developed in two phases: the first phase was accomplished in December 2019 (n=50). The second phase occurred from June to December 2021 (n=35) and the participants were contacted through phone calls or using WhatsApp. In both phases, the following surveys were filled: self-care activities with diabetes; a Self-efficacy scale concerning the handling of insulin in diabetes, and an instrument to evaluate the users’ knowledge and practices about the insulin pump system. The individual glycemic measures and the scores from the scales were compared before and after the pandemic by using the T-test of Student or Wilcoxon for related samples. Results: In comparison, it was possible to observe a decrease in the average of glycemia during fasting and the HbA1c (p<0.05). Regarding the self-care, the domains, specific feeding, and physical activity experienced a deterioration after the pandemic. In the self-efficacy scale, all domains got worse after the pandemic. The knowledge experienced a slight decrease in its domains’ score averages. Conclusions: These results highlight that despite the continuous advances in the care of diabetes, the adequate control in every field in which the disease affects requires a complex task for this public, especially in periods of a health crisis.