We studied how to achieve both the target time in range (70-180 mg/dL) [TIR] and target coefficient of variation (CV). In a cross-sectional study, we analyzed 24-h glucose levels measured using CGM (iPro2) for 150 patients with type 2 diabetes. We calculated the “mean of all absolute differences between glucose levels and the ‘reference glucose levels (R)’” (M1, in mg/dL), corresponding to 21 R (110, 111⋯130 mg/dL), as a metric to achieve the target TIR. We also calculated the “percentage of the mean absolute deviation to mean glucose levels” (M2, in %) as a metric to achieve the target CV. The R values for which M1 most correlated to TIR were 117 and 118 mg/dL (r = -0.95, p < 0.001). M2 correlated to CV (r = 0.99, p < 0.001; M2 = 0.85 × CV - 0.43). The optimal cutoff value (OC) for TIR > 70% in “M1 for R of 117.5 mg/dL” (M1, 117.5) was 44.6 mg/dL (sensitivity, 96%; specificity, 96%; AUC, 0.99; p < 0.001). The OC for CV < 36% in M2 was 31.5% (sensitivity, 100%; specificity, 100%; AUC, 1). The OC for “both TIR > 70% and CV < 36%” in “M1, 117.5 × M2,” was 842.0 (sensitivity, 90%; specificity, 89%; AUC, 0.96; p < 0.001). Putting all glucose levels close to 117.5 mg/dL may be the most efficient method to increase the TIR as much as possible. Based on our results, the simple target values are as follows: “M1, 117.5 of 42.5 mg/dL” (75-160) [if all glucose levels are within 75-160 mg/dL, M1, 117.5 is sure to be < 42.5 mg/dL] × M2 of 20% = 850 (≈ 842)” (T1); “M1, 117.5 of 27.5 mg/dL (90-145) × M2 of 30% = 825 (≈ 842)” (T2). For T1, if the range that satisfies both 75-160 mg/dL and “‘24 h mean glucose levels on the day before’ ± ‘20 % of the mean glucose levels’” (mean ± 20%) is used as an alarm threshold in a personal CGM, keeping all glucose levels within the range as much as possible may achieve both TIR > 70% and CV < 36%. For T2, if the range that satisfies both 90-145 mg/dL and mean ± 30% is used as an alarm threshold, keeping all glucose levels within the range as much as possible may achieve both TIR > 70% and CV < 36%.

Disclosure

S. Takeishi: None. T. Inoue: None.