Observational study of the relationship between the use of real-time continuous glucose monitoring and glycemic control in patients with diabetes in Japan: the REALJ study.

Although randomized controlled trials have demonstrated the efficacy of real-time continuous glucose monitoring (rtCGM), evidence from routine clinical practice remains limited, particularly in Asian populations. This study aimed to evaluate the effectiveness and safety of rtCGM initiation in individuals with diabetes. This multicenter, single-arm, retrospective, observational study was conducted at 34 sites across Japan (Clinical trial registration: UMIN000054275). Adults ≥18 years of age with diabetes who began using the Dexcom G6 rtCGM system, had a baseline glycated hemoglobin (HbA1c) level ≥7.5%, and continued rtCGM for at least 26 weeks were included. Factors associated with changes in HbA1c levels were examined using multivariate linear regression models. Among 192 participants, the mean HbA1c levels at 26 weeks were significantly lower (8.62 ± 1.14% vs. 7.88 ± 1.16%, p < 0.001) than those at baseline, with a difference of -0.73 ± 1.03%. In the multivariate analysis, greater HbA1c reduction was independently associated with higher baseline HbA1c (β = -0.40; p < 0.001), longer CGM active time (β = -0.008; p = 0.043), and older age (β = -0.010; p = 0.012), whereas prior isCGM use was associated with smaller reductions (β = +0.28; p = 0.045). Sex was also independently associated with changes in HbA1c levels (p = 0.028). During the 26-week follow-up period, one patient (0.5%) experienced diabetic ketoacidosis and four individuals (2.1%) experienced severe hypoglycemia. rtCGM initiation was associated with significantly lower HbA1c levels after 26 weeks of rtCGM use. These findings support the efficacy and safety of the Dexcom G6 in routine clinical practice.