We assessed the significance of recommendations from the international consensus on continuous glucose monitoring (CGM)-derived metrics in Japanese children and adolescents with type 1 diabetes. Eighty-five patients (age, 13.5 ± 4.7 years) who wore the FreeStyle® Libre for a 28-day period were enrolled in this study. Seventy-three patients were treated with multiple daily injections of insulin and 12 with insulin pump therapy without using a sensor-augmented pump or a predictive low-glucose suspend-function pump. We evaluated the relationship between CGM-derived metrics: time in range (TIR: 70-180 mg/dL), time below range (TBR: <70 mg/dL), and time above range (TAR: >180 mg/dL), and laboratory-measured HbA1c and estimated HbA1c (eA1c) levels calculated from the mean glucose values. The TIR was 50.7 ± 12.2% (23-75%), TBR was 11.8 ± 5.8% (2-27%), and TAR was 37.5 ± 13.5% (9-69%). The TIR was highly correlated with HbA1c level, eA1c level, and TAR, but not with TBR. An HbA1c level of 7.0% corresponded to a TIR of 55.1% (95% CI: 53.7-56.5%), whereas a TIR of 70% corresponded to an HbA1c level of 6.1% (95% CI: 5.9-6.3%). The results of eA1c levels were similar to those observed for HbA1c levels. From these findings, we conclude that low rates of a recommended TIR of 70% may be due to less use of advanced technology and insufficient comprehensive diabetes care. Ethnic characteristics including lifestyle and eating customs may have contributed to the result. CGM-derived targets must be individualized based on ethnic characteristics, insulin treatment and diabetes care, and needs of individuals with diabetes.