Continuous Glucose Monitoring (CGM) has emerged as a vital tool for managing diabetes, particularly in youth with type 1 diabetes (T1D). One of the key metrics derived from CGM data is Time-in-Range (TIR), which indicates the percentage of time a person’s glucose levels remain within a target range. Previous research has established that a TIR greater than 70% is associated with lower HbA1c levels, a long-term marker of blood glucose control.
This study, published in the Journal of Diabetes and Its Complications, aimed to explore the relationship between TIR and HbA1c levels, specifically focusing on the impact of CGM wear-time. The researchers examined a cohort of 60 youth with T1D, categorizing them based on their CGM wear-time: those with at least 70% wear-time and those with less than 70%.
Methodology
The study employed Pearson correlation coefficients to assess the relationship between TIR and HbA1c within each wear-time group. The researchers then compared these correlations using a Fisher r-to-z transformation to determine if the strength of the associations differed significantly between the two groups.
Results
Findings revealed that both groups exhibited significant correlations between TIR and HbA1c. In the group with ≥70% CGM wear-time, the correlation was strong (r = -0.800, p < .001), indicating a robust inverse relationship between TIR and HbA1c. Conversely, the group with <70% wear-time showed a weaker correlation (r = -0.404, p < .001). Notably, the difference in correlation strength between the two groups was statistically significant (z = 3.15, p = .0016).
These results suggest that while a lower CGM wear-time is associated with a weaker correlation between TIR and HbA1c, the relationship remains statistically significant. This implies that even when CGM data is limited, it may still provide useful insights into glycemic control.
What this study does not show
This study does not establish a causal relationship between CGM wear-time and HbA1c levels, nor does it provide evidence on the clinical outcomes of adjusting diabetes management based on TIR data from lower wear-time.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Established
- Clinical utility: Partial
The evidence is based on primary research conducted with human participants.