Effectiveness of continuous glucose monitoring systems on glycemic control in adults with type 1 diabetes: A systematic review and meta-analysis.

INTRODUCTION

Continuous glucose monitoring (CGM) technologies have been advancing rapidly, but evidence on their comparative effectiveness stills limited to date yet. We conducted a systematic review and meta-analysis to evaluate and investigate the impact of CGM systems on glycemic control in adults with type 1 diabetes.

METHODS

We searched electronic literature databases from inception through April 30, 2025, for comparative studies investigating CGM systems with standard monitoring or different CGM technologies in adults with type 1 diabetes. Primary outcomes included HbA1c reduction, time in range (TIR), and hypoglycemia reduction. We performed random-effects meta-analyses, network meta-analysis, and subgroup analyses by baseline HbA1c and intervention duration. Evidence quality was assessed using GRADE methodology.

RESULTS

Twenty-seven studies with total of 2975 participants were included. CGM significantly reduced HbA1c compared to standard monitoring (mean difference: 0.38 %, 95 % CI: 0.49 to -0.27 %). TIR increased by 7.9 % (95 % CI: 5.8-10.0 %), representing 114 additional minutes daily in best range. Real-time CGM showed advantages over intermittently scanned CGM for TIR (+5.63 %, P-value<0.001) and hypoglycemia reduction (-1.28 %, P-value<0.001). Automated closed-loop systems achieved the highest ranking in network meta-analysis (SUCRA = 0.92). Benefits were greater among patients with higher baseline HbA1c (>8.5 %: 0.68 % reduction in HbA1c vs. <7.5 %: 0.24 % reduction in HbA1c, P-value = 0.009).

CONCLUSIONS

CGM technologies significantly improve glycemic control in adults with type 1 diabetes, with greater benefits for those with higher baseline HbA1c. Advanced systems demonstrate progressively greater improvements, with automated closed-loop systems showing the strongest evidence of effectiveness. These findings support broader implementation of CGM technologies, with selection tailored to individual patient needs.