Impact of Switching from Intermittently Scanned to Real-Time Continuous Glucose Monitoring Systems in a Type 1 Diabetes Patient French Cohort: An Observational Study of Clinical Practices

Abstract

Aim: Assess the impact of switching from intermittently scanned (FreeStyle Libre [FSL]) to real-time (Dexcom G4 platinum [DG4]) continuous glucose monitoring systems on glycemia control in type 1 diabetes (T1D) patients with high risk of hypoglycemia and/or elevated glycated hemoglobin (HbA1c). Methods: We conducted an observational study in 18 T1D adults with poor glycemic control on FSL. Ambulatory glucose profile data were collected during the last 3 months of FSL use before inclusion (M0 period), during the first 3 months (M3 period) and the last 3 months (M6 period) of DG4 use. Data were then expressed as 24-h averages. Biological HbA1c was measured for all three periods. Patients were their own-controls and statistics were performed using paired t-test or Wilcoxon for matched-pairs. Results: The switch to DG4 at M3 resulted in a higher time-in-range (TIR) 70-180 mg/dL (median [Q1;Q3], 53.1 [44.5;67.3] vs. 41.5 [28.5;62.0], P = 0.0008), and a lower time-below-range <70 mg/dL (TBR meanstandard deviation (SD), 5.4 -3.7 vs. 10.9 -7.1, P = 0.0009) and in the glucose % coefficient of variation (%CV mean -SD, 40.1 vs. 46.9, P = 0.0001). Mean (SD) changes were +10.3 (8.0) percentage points for TIR, -5.5 (5.8) percentage points for TBR, and -6.8 (5.8) percentage points for %CV. These results were confirmed at the M6 period. Conclusions: Switching from FSL to DG4 appears to provide a beneficial therapeutic option without changing insulin delivery systems, regardless of the origin of the patient's initial glycemic issue.

Benefits of a Switch From Intermittently Scanned Continuous Glucose Monitoring (isCGM) to Real-time (rt) CGM in Diabetes Type 1 Suboptimal Controlled Patients in Real-life: A One-year Prospective Study

“…As discussed already in our previous mid-term switch-study [14], the explanations for glucose benefits reported over one year (TIR, TBR, %CV) is probably the consequence of switching to DG4 in combination with appropriate education follow-up (TPE program, the need for daily calibrations reinforcing the investment in the daily management of diabetes, threshold hypo/hyperglycemic alarms increasing the ability of patients to respond properly to glycemic excursions) [8]. More specifically, the prolonged or accentuated benefit, respectively, in %CV or TBR is corroborated by the existence of a positive strong association between these metrics as shown in our previous mid-term study [14], and confirmed herein, recalling that the intraday variability of glucose is largely influenced by exposure to hypoglycemia at different thresholds, and for any average interstitial glucose value [18]. To note that our TBR values were in the range of those obtained in T1D patients using Dexcom G4, G5 or G6 for at least 3 months, with a close hypoglycemia alarm threshold (<73 mg/dL) giving TBR<70mg/dL and TBR<54mg/dL around 4.7% and 1.5%, respectively [19].…”

“…In the light of our previous study [14], our objective was to assess the potential persistent long-term benefit of switching from FSL1 to DG4 on glycemic control using metrics from the Ambulatory Glucose Parameters (AGP) report. The main evaluation criteria selected were TIR 70-180 mg/dL, TBR<70 mg/dL, TBR<54 mg/dL, TAR>180 mg/dL, TAR>250 mg/dL, average IG concentration, glycemic variability as %CV, GMI, the CGM system utilization rate and biological HbA1c.…”

“…Patients taking advantage of switching to DG4 participated in a therapeutic patient educational (TPE) program conducted by trained diabetologists and nurses, to promote adherence to the new sensor. Details regarding the TPE program are given in Figure 1 (Study design) and in our previous study [14].…”

“…For a patient already using CGM device but considered in treatment failure based on elevated HbA1c and/or persistent hypoglycemia issue, studies focussing on the effectiveness of a device switch seem more appropriate and therefore required [11]. In that purpose, we recently conducted and published an observational study in 18 T1D adult patients with suboptimal glycemic control (hypoglycemia issue and/or elevated HbA1c) despite using an isCGM sensor (Freestyle Libre version 1 or FSL1, Abbott Diabetes Care Inc.), and taking advantage switching to rtCGM sensor (Dexcom G4 or DG4, Dexcom Inc.) over a follow-up of 6 months [14]. We observed a clinically relevant increase in TIR (+9.5 percentage points or pp; P = 0.0015), a decrease in TBR<70mg/dL (-4.8 pp; P = 0.0044) and in the %CV (-4.6 pp; P = 0.0002), and no change in Time-Above-Range (TAR).…”

“…We observed a clinically relevant increase in TIR (+9.5 percentage points or pp; P = 0.0015), a decrease in TBR<70mg/dL (-4.8 pp; P = 0.0044) and in the %CV (-4.6 pp; P = 0.0002), and no change in Time-Above-Range (TAR). However, benefits plateaued between 3 and 6 months of DG4 use [14] raising the question about long-term improvements.…”