Resistance to Data Loss of Glycemic Variability Measurements in Long-Term Continuous Glucose Monitoring.

BACKGROUND Continuous glucose monitoring (CGM) is a method of estimating blood glucose values from those recorded in the interstitial fluid. Because increasingly longer CGM measurements are possible, errors and data loss become more and more likely and potentially more damaging to accurate calculations of glycemic variability (GV) indices. Our research investigates the resistance of the CGM recording to data loss. METHODS We collected 71 CGM recordings (duration of min: 2, max: 265, median: 42 days) from patients with type 1 diabetes and used three algorithms to introduce missing data. We calculated mean and standard deviation (SD) of absolute percentage error of 12 variability indices and correlated those with the percentage of missing data and duration of the measurements. RESULTS Mean absolute percentage error of variability indices increased linearly with the percentage of missing data along with SD of absolute percentage error. Except for mean amplitude of glycemic excursions and time spent in hypoglycemia, all absolute errors never exceeded 25%, while mean absolute errors stayed below 5%. The gradient removal algorithm introduced errors larger than the single datapoint and block removal algorithms. The absolute percentage error of variability indices correlated negatively with the duration of the CGM measurements. CONCLUSIONS Standard GV measurements in long-term glucose monitoring are robustly resistant to data loss.