Continuous Glucose Monitors Boost the Effectiveness of Diabetes Drugs — Especially GLP-1 Medications

What the researchers found

Among over 52,000 adults with type 2 diabetes not using insulin, adding continuous glucose monitoring (CGM) was associated with a 0.45% greater HbA1c reduction compared to not using CGM (p<0.0001). The benefit of CGM was particularly pronounced when combined with GLP-1 receptor agonists, DPP-4 inhibitors, and sulfonylureas — these medications showed statistically significant interaction effects, meaning CGM amplified their glucose-lowering benefits more than it did for metformin or SGLT2 inhibitors.

Why it matters

CGM has been primarily studied in people using insulin, but most type 2 diabetes patients don't use insulin. This large study shows that CGM provides meaningful additional blood sugar control when paired with oral and injectable non-insulin medications, particularly GLP-1 drugs — supporting broader insurance coverage and clinical adoption of CGM technology.

The numbers in context

n=52,394 · 4,086 CGM users vs 48,308 non-users · -0.45% greater A1c change · p<0.0001 · Significant interactions for GLP-1 RAs, DPP-4i, sulfonylureas

How the study worked

Retrospective observational analysis of the Optum Clinformatics Data Mart database (administrative claims + linked lab data) from July 2018 through June 2023. CGM-naïve adults with non-insulin-treated type 2 diabetes using at least one of five anti-diabetes medication classes were identified. 6-month baseline and follow-up periods. Linear regression models tested main and interaction effects of CGM use with each medication class.

Who was studied

52,394 CGM-naïve adults with non-insulin-treated type 2 diabetes using anti-diabetes medications (US claims database)

What this study cannot tell us

Observational design cannot prove causation — CGM users may be more engaged with their health, leading to confounding. The study uses administrative claims which may not capture all relevant clinical variables. It does not distinguish between different CGM devices or assess how patients used CGM data to modify behavior.

How to read the evidence

Large observational study (52,394 patients) using comprehensive claims data with linked lab results. The sample size is a major strength, but the observational design and potential for selection bias (healthier, more engaged patients choosing CGM) prevent causal conclusions.

When this study was published

Published in 2025 with data through 2023, this is very current research reflecting modern CGM technology and the growing use of GLP-1 drugs in type 2 diabetes management.

The bigger picture

CGM technology has been transformative for insulin-dependent diabetes management, but insurance coverage for non-insulin users has been limited. This study provides large-scale evidence that CGM adds value even without insulin, particularly when paired with incretin-based therapies like GLP-1 drugs. As GLP-1 drug use expands rapidly, combining them with CGM could optimize outcomes.

Questions still open

• What behaviors do CGM users change that lead to better A1c — diet, timing, medication adherence?
• Would a randomized trial confirm the synergy between CGM and GLP-1 drugs seen in this observational data?
• Is the CGM benefit sustained beyond the 6-month follow-up period?

Common questions

Read the original research

Exploring Combined Use of Continuous Glucose Monitoring and Anti-Diabetes Medications on Glycaemic Control for People With Type 2 Diabetes Not Using Insulin.

Endocrinology, diabetes & metabolism, 8(5), e70089

Citation

Nemlekar, Poorva M; Hannah, Katia L; Green, Courtney R; Norman, Gregory J. (2025). Exploring Combined Use of Continuous Glucose Monitoring and Anti-Diabetes Medications on Glycaemic Control for People With Type 2 Diabetes Not Using Insulin.. Endocrinology, diabetes & metabolism, 8(5), e70089. https://doi.org/10.1002/edm2.70089