Abstract
BackgroundThe validity of continuous glucose monitoring (CGM) is well established in diabetic patients. CGM is also increasingly used for research purposes in normo-glycemic individuals, but the CGM validity in such individuals is unknown. We studied the accuracy of CGM measurements in normo-glycemic individuals by comparing CGM-derived versus venous blood-derived glucose levels and measures of glycemia and glycemic variability.MethodsIn 34 healthy participants (mean age 65.7 years), glucose was simultaneously measured every 10 minutes, via both an Enlite® CGM sensor, and in venous blood sampled over a 24-hour period. Validity of CGM-derived individual glucose measurements, calculated measures of glycemia over daytime (09:00h-23:00h) and nighttime (23:00h-09:00h), and calculated measures of glycemic variability (e.g. 24h standard deviation [SD]) were assessed by Pearson correlation coefficients, mean absolute relative difference (MARD) and paired t-tests.ResultsThe median correlation coefficient between CGM and venous glucose measurements per participant was 0.68 (interquartile range: 0.40–0.78), and the MARD was 17.6% (SD = 17%). Compared with venous sampling, the calculated measure of glycemia during daytime was 0.22 mmol/L higher when derived from CGM, but no difference was observed during nighttime. Most measures of glycemic variability were lower with CGM than with venous blood sampling (e.g., 24h SD: 1.07 with CGM and 1.26 with venous blood; p-value = 0.004).ConclusionIn normo-glycemic individuals, CGM-derived glucose measurements had good agreement with venous glucose levels. However, the measure of glycemia was higher during the day and most measures of glycemic variability were lower when derived from CGM.
Highlights
Continuous glucose monitoring (CGM) is a minimally invasive method that has been approved for ambulant glucose monitoring in patients with diabetes mellitus [1]
The calculated measure of glycemia during daytime was 0.22 mmol/L higher when derived from continuous glucose monitoring (CGM), but no difference was observed during nighttime
Most measures of glycemic variability were lower with CGM than with venous blood sampling (e.g., 24h standard deviation (SD): 1.07 with CGM and 1.26 with venous blood; p-value = 0.004)
Summary
Continuous glucose monitoring (CGM) is a minimally invasive method that has been approved for ambulant glucose monitoring in patients with diabetes mellitus [1]. For the purpose of patient care, the validity of different CGM devices has been studied against glucose measures obtained with another CGM device [2], glucometers [3, 4], capillary blood [5, 6] and venous blood taken at random time points [7]. Studies have been conducted in which CGM glucose measurements were compared with frequently sampled venous blood glucose measurements [8,9,10,11]. The device provides information on 24-hour glucose rhythms for up to six consecutive days From this data, measures of glycemia and glycemic variability can be calculated. We studied the accuracy of CGM measurements in normo-glycemic individuals by comparing CGM-derived versus venous bloodderived glucose levels and measures of glycemia and glycemic variability
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