Optimal Sampling Intervals to Assess Long-Term Glycemic Control Using Continuous Glucose Monitoring
- 1 March 2011
- journal article
- research article
- Published by Mary Ann Liebert Inc in Diabetes Technology & Therapeutics
- Vol. 13 (3), 351-358
- https://doi.org/10.1089/dia.2010.0156
Abstract
Aims and Hypothesis: The optimal duration and frequency of short-term continuous glucose monitoring (CGM) to reflect long-term glycemia have not been determined. The Juvenile Diabetes Research Foundation CGM randomized trials provided a large dataset of longitudinal CGM data for this type of analysis. Methods: The analysis included 185 subjects who had 334 3-month intervals of CGM data meeting specific criteria. For various glucose indices, correlations (r2) were computed for the entire 3-month interval versus selected sampling periods ranging from 3 to 15 days. Other computed agreement measures included median relative absolute difference, values within ± 10% and ± 20% of full value, and median absolute difference. Results: As would be expected, the more days of glucose data that were sampled, the higher the correlation with the full 3 months of data. For 3 days of sampling, the r2 value ranged from 0.32 to 0.47, evaluating mean glucose, percentage of values 71–180 mg/dL, percentage of values >180 mg/dL, percentage of values ≤70 mg/dL, and coefficient of variation; in contrast, for 15 days of sampling, the r2 values ranged from 0.66 to 0.75. The results were similar when the analysis intervals were stratified by age group (8–14, 15–24, and ≥25 years), by baseline hemoglobin A1c level (Conclusions and Interpretation: Our data suggest that a 12–15-day period of monitoring every 3 months may be needed to optimally assess overall glucose control. Shorter periods of sampling can be useful, but the correlation with 3-month measures of glycemic control is lower.Keywords
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