Abstract
Objective: To evaluate the impact of prolonged hybrid closed loop (HCL) use in children with type 1 diabetes (T1D) on glucose control and BMI throughout pubertal progression.Research design and methods: We used a prospective multicenter extension study following the Free-Life Kid AP (FLKAP) HCL trial. The 9-month previously reported FLKAP trial included 119 prepubertal children (aged 6-12 years). During the extension study, participants could continue to use HCL for 30 months (M9 to M39). HbA1c values were collected every 3 months up to M39, while continuous glucose monitoring metrics, BMI Z scores, and Tanner stages were collected up to M24. Noninferiority tests were performed to assess parameter sustainability over time.Results: One hundred seventeen children completed the extension study, with mean age 10.1 years (min-max 6.8-14.0) at the beginning. Improvement of HbA1c obtained in the FLKAP trial was significantly sustained during extension (median [interquartile range], M9: 7.0% [6.8-7.4], and M39: 7.0% [6.6-7.4], P < 0.0001 for noninferiority test) and did not differ between children who entered puberty at M24 (Tanner ≥ stage 2; 54% of the patients) and patients who remained prepubertal. BMI Z score also remained stable (M9: 0.41 [-0.29 to 1.13] and M24: 0.48 [-0.11 to 1.13], P < 0.0001, for noninferiority test). No severe hypoglycemia and one ketoacidosis episode not related to the HCL system occurred.Conclusions: Prolonged use of HCL can safely and effectively mitigate impairment of glucose control usually associated with pubertal progression without impact on BMI in children with T1D.