The Continuous Glucose Monitoring System during pregnancy of women with type 1 diabetes mellitus: accuracy assessment

Abstract

Background: The Continuous Glucose Monitoring System (CGMS, Medtronic MiniMed, Northridge, CA) allows close monitoring of glucose patterns and might be helpful in explaining the persistence of high complication rates in pregnancies of women with type 1 diabetes. It was the aim of this study to determine whether the CGMS accurately reflects glucose levels in pregnant women with type 1 diabetes mellitus.

Methods: Fifteen pregnant women with type 1 diabetes used the CGMS and were asked to determine at least seven fingerstick blood glucose levels each day, of which four were used for calibration. The patients were asked to keep a diary of the non-calibration blood glucose values. The accuracy of the CGMS was studied by comparing the non-calibration blood glucose values with simultaneously measured sensor glucose values using the Pearson correlation coefficient, the mean of absolute differences, and the Clarke error grid analysis.

Results: A total of 239 non-calibration blood glucose values were analyzed. The correlation coefficient between non-calibration blood glucose and sensor glucose value was 0.94 (P < 0.001). The mean of the absolute difference was 0.74 mmol/L. Of the non-calibration data 93.8% fell in the clinically acceptable zone of the Clarke error grid analysis.

Conclusions: The CGMS is an accurate tool for additional glucose monitoring in pregnant women with type 1 diabetes mellitus.