Navigating the Future: Considerations for use of Continuous Glucose Monitoring in Diabetes Trials

A continuous glucose monitoring system (CGM) is a digital health technology (DHT) device that measures interstitial glucose. CGMs are used in the management of diabetes. The purpose of this study was to retrospectively assess the quality of CGM data in a clinical trial involving patients with type 1 diabetes.

CGM data were collected from 461 patients with type 1 diabetes who participated in a 16-week, double-blind phase 3 trial designed to examine the efficacy of prandial (mealtime) insulins. CGM data were collected at three 2 week study time points. The patterns of missing CGM data (due to non-wear, user- and device-related causes) and the relationship between CGM metrics and hemoglobin A1C (HbA1c) were examined using data visualization approaches.

Across the three observation periods, 4.7-6% of CGM observations were missing. Approximately 16% of daily values were missing on days when a new CGM sensor was inserted. For many patients, high glucose variability was associated with low time in range (TIR) and HbA1c >7%. Conversely, low glucose variability was associated with higher TIR.

Our analysis identified the need for adequate documentation indicating the presence of patient- and device-related events (e.g., sensor changes, non-wear time) to address causes of missing CGM data. These causes need to be considered prior to the statistical assessment of such data for research and regulatory purposes. Accurate documentation of post-baseline events is important for the development of research and regulatory standards for the collection and analysis of data acquired from DHTs.