Effect of Real-Time Continuous Glucose Monitoring Versus Flash Glucose Monitoring on Glycemic Control in Adults with Type 1 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Objective: This meta-analysis aimed to compare the effect of the real-time continuous glucose monitoring (rt-CGM) and flash glucose monitoring (FGM) on glycemic control in adults with type 1 diabetes mellitus (T1DM). Methods: A systematic literature search of all relevant studies comparing the clinical effectiveness of rt-CGM and FGM in adults with T1DM on Cochrane Library, PubMed, Embase, Web of Science, and Scopus from January 2015 to June 2023 was performed. The primary endpoints were glycated hemoglobin (HbA1c) and TIR (time in range). Secondary endpoints included time below range [TBR (<3.9 mmol/L) and (<3.0 mmol/L)], time above range [TAR (>10.0 mmol/L) and (>13.9 mmol/L)], mean glucose, and glycemic variability (GV) [standard deviations (SD) and coefficient of variation (CV)]. Results: Six studies with 1516 TIDM patients, including three randomized controlled trials and three observational studies, were enrolled in this meta-analysis. Compared to FGM, rt-CGM led to greater glycemic control, represented by higher TIR (%, 3.9 ∼ 10 mmol/L) (SMD = 0.59, 95% CI: 0.37 ∼ 0.81, p < 0.001), decreased TBR (%, <3.9 mmol/L) (SMD = -1.45, 95% CI: -2.33 ∼ -0.57, p = 0.001), decreased TAR [(%, >10.0 mmol/L) (SMD = -0.38, 95% CI: -0.71 ∼ -0.04, p = 0.03) and (%, >13.9 mmol/L) (SMD = -0.42, 95% CI: -0.79 ∼ -0.04, p = 0.03), respectively], lower mean glucose (SMD = -0.18, 95% CI: -0.31 ∼ -0.06, p = 0.003), decreased SD (SMD = -0.70, 95% CI: -1.09 ∼ -0.31, p < 0.001), and decreased CV (SMD = -0.76, 95% CI: -1.05 ∼ -0.47, p < 0.001). However, there was no difference in lowering HbA1c and TBR (%, <3.0 mmol/L) between groups. Conclusion: The rt-CGM outperformed FGM in improving several key CGM metrics among adults with T1DM, but there is no significant difference in HbA1c and TBR (<3.0 mmol/L).