Introduction: Continuous glucose monitoring system is a valuable instrument to measure glycemic control, which uses a retrospective calibration based upon 3 to 4 capillary glucose meter values inserted by the patient each day.
Objective: We evaluated the interference of calibration during the dawn period in the system accuracy.
Methods: The monitoring data were retrospectively divided into two groups: with (Group A) or without (Group B) the dawn period calibration (between 1:00 and 5:00 AM). Accuracy of the method was expressed by relative absolute difference.
Results: Thirty-four continuous glucose monitoring data were evaluated comprising a total of 112 nights. A total of 289 paired readings were analyzed - 195 in Group A and 94 in Group B. We did not find a difference in relative absolute difference (RAD%) in any analyzed period of day by adding dawn calibration.
Conclusions: These data suggest that dawn calibration does not alter accuracy of method.