Flash glucose (FGMS) and continuous glucose (CGMS) monitoring systems are becoming increasingly prevalent in clinical practice. We directly compared FGMS (FreeStyle Libre-Pro, FSL-Pro) and CGMS (iPro2) in a patient with diabetes mellitus (T1DM/T2DM = 3/10). Analysis of 7,365 paired values revealed a close correlation between FSL-Pro and iPro2 glucose values (r = 0.93, p < 0.01). Parkes error grid analysis showed that 93.3%, 6.2%, 0.5% and 0.04% of all glucose pairs fell within areas A, B, C and D, respectively, whereas no values was located in area E. Median glucose values were significantly lower for FSL-Pro than iPro2 (149.0 (115.0-187.0) vs. 171.0 (138.0-213.0) mg/dL, p < 0.01). Notably, 89.3% of all glucose values were lower for FSL-Pro than iPro2; therefore, the difference between them was considerable (Figure 1; r = -0.273, p < 0.01). The absolute difference between FSL-Pro and iPro2 glucose values was significantly higher among hyperglycemic values (>180 mg/dL) compared with normoglycemic values (70-180 mg/dL) (32.0 (19.0-47.0) vs. 23.0 (14.0-31.0) mg/dL, p < 0.05). We concluded that glucose values are lower when measured using FSL-Pro than iPro2 and this tendency became more pronounced under conditions of hyperglycemia.

R. Kumagai: None. A. Muramatsu: None. M. Fujii: None. Y. Katakura: None. K. Fujie: None. Y. Nakata: None. K. Hashimoto: None. H. Yagyu: None.

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