CGM improves glycemic metrics in T2D

Methodology

The review systematically identified and synthesized randomized controlled trials (RCTs) assessing the effects of CGM versus SMBG in T2DM patients. Studies were selected using predefined inclusion/exclusion criteria and screened in duplicate. Data were extracted on patient characteristics, types of CGM, outcomes (HbA1c, time in range, time in hyper/hypoglycemia), and intervention details. Risk of bias was assessed using the Cochrane ROB 2.0 tool. Meta-analysis was conducted using random-effects models with Hartung-Knapp-Sidik-Jonkman adjustments to account for variability and heterogeneity.

GRADE methodology was applied to assess certainty of evidence across outcomes. Funnel plots and Egger regression were used to assess publication bias. Subgroup and sensitivity analyses were performed based on insulin use, baseline HbA1c, and diabetes duration. The data synthesis focused on percentage mean differences and confidence intervals for glycemic outcomes.

Interventions

Interventions included the use of real-time CGM (Dexcom G4, G6, 7, etc.) and flash CGM (FreeStyle Libre, Libre Pro) as alternatives to SMBG. Devices varied in terms of duration, training provided, and frequency of data collection. Some trials used episodic CGM, while others applied continuous use. CGM was used either blinded or unblinded, depending on the study. Most interventions aimed at optimizing diabetes self-management by offering patients real-time data for glucose trends and alerts, improving behavioral responses to glycemic fluctuations.

Key Findings

CGM use in T2DM resulted in modest yet statistically significant HbA1c reductions (approximately 0.32%), with both rt-CGM and FGM yielding similar results. rt-CGM showed an 11% increase in time in range, though changes in time in hyperglycemia and hypoglycemia were not consistently significant. The certainty of evidence was moderate for primary outcomes, and patient satisfaction was generally favorable. However, longer-term outcomes and adverse event reporting were limited across included trials, suggesting the need for extended studies to assess clinical impact and cost-effectiveness more fully.

Comparison with other Studies

Previous studies primarily focused on CGM in type 1 diabetes populations, where consistent benefits in glucose control and hypoglycemia prevention were reported. This review contrasts by focusing on T2DM patients, a more diverse group in terms of treatment regimens and glycemic variability. Compared to earlier meta-analyses, this study included more recent trials and employed robust sensitivity analysis and bias assessment. The findings are aligned with prior small-scale studies and reviews but provide stronger evidence by aggregating a larger sample with improved methodological rigor.

While this review confirms the HbA1c-lowering benefit of CGM in T2DM, it also highlights variability in hypoglycemia outcomes and limited evidence for long-term benefits such as reduced complications or hospital visits. These inconsistencies were also noted in prior work, which emphasized the importance of subgroup stratification. By focusing on adults using mixed treatment regimens and analyzing rt-CGM and FGM separately, the current study provides a clearer picture of CGM's role across a wider clinical landscape.

Journal Reference

Uhl S, Choure A, Rouse B, Loblack A, Reaven P. Effectiveness of Continuous Glucose Monitoring on Metrics of Glycemic Control in Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Randomized Controlled Trials. J Clin Endocrinol Metab. 2024;109(4):1119–1131. doi:10.1210/clinem/dgad652