Continuous Glucose Monitoring (CGM) has become an essential tool in managing diabetes, particularly for individuals with type 1 diabetes (T1D). One of the key metrics derived from CGM data is Time-in-Range (TIR), which reflects the percentage of time a patient’s glucose levels remain within a target range. Previous research has indicated that maintaining a TIR greater than 70% is associated with lower HbA1c levels, a common measure of long-term glucose control.
This study, published in the Journal of Diabetes and Its Complications, explores the relationship between CGM wear-time and the TIR-HbA1c association among youth with T1D. The research involved 60 participants who were divided into two groups based on their CGM wear-time: those with ≥70% wear-time and those with <70% wear-time.
Methodology
The authors calculated Pearson correlations between TIR and HbA1c for each wear-time group. They then compared these correlations using a Fisher r-to-z transformation to determine if the strength of the association differed significantly between the two groups.
Results
The findings revealed that both groups exhibited significant correlations between TIR and HbA1c. Specifically, the group with ≥70% wear-time showed a strong negative correlation (r = -0.800, p < .001), indicating that higher TIR was associated with lower HbA1c levels. Conversely, the group with <70% wear-time had a weaker correlation (r = -0.404, p < .001). The statistical analysis indicated that the association in the ≥70% group was significantly stronger than in the <70% group (z = 3.15, p = .0016).
Conclusion
While the correlation between TIR and HbA1c was weaker in the <70% wear-time group, the results still achieved statistical significance. This suggests that even with lower CGM wear-time, there may be some utility in relying on TIR data when necessary. However, the authors emphasize the importance of maximizing CGM wear-time to enhance the reliability of TIR measurements and their implications for HbA1c levels.
What this study does not show
This study does not establish a causal relationship between CGM wear-time, TIR, and HbA1c, nor does it provide evidence on the long-term health outcomes associated with varying CGM wear-times.
Evidence scorecard
- Analytic validity: established
- Clinical validity: established
- Clinical utility: not established
The evidence is based on primary research involving human participants.