The coefficient of variation (CV) of CGM-derived sensor glucose values (SGVs) is the preferred metric for glycemic variability. However, a high CV is not directly actionable. We hypothesized that overtreatment of hyperglycemia (leading to iatrogenic lows) and overtreatment of hypoglycemia (leading to rebound highs) contribute to excessive CVs. An iatrogenic low was defined as any series of SGVs <70 mg/dL starting within 2 h of an SGV >180 mg/dL; a rebound high was any series of SGVs >180 mg/dL starting within 2 h of an SGV <70 mg/dL. We used data from a convenience sample of anonymized U.S.-based users of G6 CGM systems (Dexcom) who had uploaded >80% of possible SGVs over >28 days in 3Q2019. Users were stratified into quartiles by CV. Cohorts with CVs <31.2% ("Stable") or >39.1% ("Labile") were compared with respect to rebound highs, iatrogenic lows, the percentage of SGVs <70 or >180 mg/dL (TBR and TAR, respectively), and the fraction meeting TAR and TBR goals of <25% and <4%, respectively. Compared to "Stable" users, the iatrogenic lows and rebound highs of "Labile" users were more frequent and longer. Users in the "Stable" cohort also had lower TAR and TBR percentages than users in the "Labile" cohort and were more likely to meet consensus goals for these metrics (Table). Patients may lower CV and improve other CGM metrics by focusing on avoiding overtreatment of high and low glucose values.
K.J. Leone: Employee; Self; Dexcom, Inc. G. Acciaroli: Employee; Self; Dexcom, Inc. A. Parker: Employee; Self; Dexcom, Inc. Stock/Shareholder; Self; Dexcom, Inc. J. Welsh: Employee; Self; CSL Behring. T.C. Walker: Employee; Self; Dexcom, Inc. D.A. Price: Employee; Self; Dexcom, Inc.