FreeStyle Libre System (FSL) is a minimally invasive technology, which provides frequent information about interstitial glucose levels, which allows adjustment of insulin dose and a reduction in the number of fingersticks. This study aims to evaluate the effectiveness and safety of FSL in childhood and adolescence.

Prospective case series in 27 Spanish hospitals. Patients aged 4-17 years with type 1 diabetes mellitus (T1DM) were included. Follow-up was done at 3, 6 and 12 months after starting to use the FSL. Outcome measures were HbA1c levels, acute complications of DM (severe hypoglycemia, ketoacidosis), DM knowledge, health-related quality of life, satisfaction and adverse effects. Biochemical glycemic outcomes (e.g., glycemic variability, time in therapeutic range) were available from 3 to 12 months. Mixed regression models with repeated time measurements were implemented.

The mean age of patients was 12.6 years, with 56.4 percent had HbA1c values above 7.5 percent at baseline. This subgroup significantly improved their HbA1c levels at 3, 6 and 12 months (-0.46%, -0.44% and -0.35%, respectively). Patients with controlled HbA1c levels significantly worsened at 12 months (0.29%). There was a significant reduction in severe hypoglycemic episodes, but only in the multiple imputation analysis. In patients controlled at baseline, there were significant reductions between 3 and 12 months in the percentage of time under 55mg/dl (-0.64%), above 250mg/dl (-1.8%) and glycemic variability (-2.6%). In uncontrolled patients, there was a significant reduction in time above 250mg/dl (-5.8%) between 3 and 12 months follow-up. There was no significant improvement in knowledge about disease, although general self-perceived health worsened and general satisfaction improved. Mild adverse events such as skin reactions (14%) and discomfort or pain (11.3%) with no significant reductions in follow-up were recorded.

The use of FSL in childhood and adolescence with T1DM produces a significant reduction in HbA1c levels in patients with uncontrolled HbA1c levels along with a reduction in severe hypoglycemic episodes (in the multiple imputation analysis). FSL-related adverse effects are considered mild.