Frequent Continuous Glucose Monitoring Significantly Improves Glycemic Control in Type 2 Diabetes: JAMA

Poor glycemic control is the fundamental driver of diabetes-related complications, and while CGM adoption has increased in the management of type 2 diabetes, evidence linking frequency of use to measurable clinical outcomes has remained scant. This large-scale study fills that gap by analyzing real-world data to establish a clear relationship between CGM usage patterns and HbA1C outcomes over 12 months.

This retrospective, propensity score–matched, cross-sectional study used Optum deidentified Market Clarity Data, including insurance claims and electronic medical records collected from January 1, 2019, through December 31, 2023. The dataset included clinical information for 6 months before each participant's index date and 12 months of follow-up.

The study population included 9,258 adults aged 18 years or older with type 2 diabetes and baseline HbA1C levels between 7.0% and 15.0%. The participants were stratified into five groups based on the frequency of CGM use during the 12-month postindex period:

• Control group (no CGM use): 4,629 patients

• Frequency 1 (≥1 to ≤90 days): 1,081 patients

• Frequency 2 (>90 to ≤180 days): 523 patients

• Frequency 3 (180 to ≤270 days): 540 patients

• Frequency 4 (>270 days): 2,485 patients

Change in HbA1C was analyzed relative to the frequency of CGM use compared to no CGM use by using mixed-model statistical methods.

Results

• The mean (SD) age of participants was 55.9 (10.6) years, with 45.4% female (4,207 patients).

• The primary outcome-change in HbA1C levels-showed a strong positive correlation between higher CGM use and greater improvement in glycemic control.

• At 12 months, the high-frequency CGM group (frequency 4) had the greatest HbA1C reduction of −1.52 percentage points (95% CI, −1.73 to −1.32), compared with a reduction of only −0.63 percentage points (95% CI, −0.80 to −0.45) in the no CGM group.

Early improvements were evident at approximately 3 months, where all CGM user groups demonstrated significantly greater HbA1C reductions than controls:

• Frequency 1: −0.59 percentage points (95% CI, −0.96 to −0.21)

• Frequency 2: −0.57 percentage points (95% CI, −1.10 to −0.05)

• Frequency 3: −0.79 percentage points (95% CI, −1.25 to −0.34)

• Frequency 4: −0.91 percentage points (95% CI, −1.12 to −0.70)

• Control group: −0.28 percentage points (95% CI, −0.47 to −0.09)

• Most notably, there was no additional improvement beyond 6 months for CGM users in both frequency 2 and 3 groups, suggesting that partial or intermittent use does not confer continued benefits.

• By contrast, patients in frequency 1 and frequency 4 groups had sustained glycemic improvements over the entire follow-up period.

• The combination of frequent CGM use with a GLP-1 RA yielded even greater glycemic benefit, with a mean HbA1C treatment difference of −1.13 percentage points (95% CI, −1.46 to −0.80) compared with non-CGM users.

The present study found that frequent continuous glucose monitoring was associated with significantly better HbA1C outcomes in adults with type 2 diabetes compared with infrequent or no CGM use. The findings reinforce that continuous and consistent CGM use is necessary to achieve long-term glycemic stability and that clinicians should foster adherence and review CGM utilization on a regular basis to optimize therapeutic outcomes.

Reference:

Hirsch IB, Garg SK, Repetto E, et al. Continuous Glucose Monitoring Frequency and Glycemic Control in People With Type 2 Diabetes. JAMA Netw Open. 2025;8(10):e2539278. doi:10.1001/jamanetworkopen.2025.39278