Careful readings for a flash glucose monitoring system in nondiabetic Japanese subjects: individual differences and discrepancy in glucose concentrarion after glucose loading [Rapid Communication]

• Published in: ENDOCRINE JOURNAL Vol. 64; no. 8; pp. 827 - 832
• Main Authors: Sekido, Keiko, Sekido, Takashi, Kaneko, Atsuko, Hosokawa, Manami, Sato, Ai, Sato, Yoshihiko, Yamazaki, Masanori, Komatsu, Mitsuhisa
• Format: Journal Article
• Language: English
• Published: Japan The Japan Endocrine Society 01.01.2017; Japan Science and Technology Agency
• Subjects: Adult; Blood Glucose - analysis; Blood Glucose Self-Monitoring; Female; Flash glucose monitoring; Glucose; Glucose monitoring; Glucose tolerance; Glucose Tolerance Test; Healthy Volunteers; Humans; Hyperglycemia; Hyperglycemia - blood; Hypoglycemia; Hypoglycemia - blood; Individuality; Interstitial fluid glucose; Japan; Male; Middle Aged; Monitoring, Ambulatory; Flash glucose monitoring; Interstitial fluid glucose
• ISSN: 0918-8959; 1348-4540
• DOI: 10.1507/endocrj.EJ17-0193

The FreeStyle Libre Flash Glucose Monitoring System (FGM), which can continuously measure glucose concentration in the interstitial fluid glucose (FGM-ISFG), has been in clinical use worldwide. However, it is not clear how accurately FGM-ISFG reflects plasma glucose concentration (PG). In the present study, we examined the clinical utility of FGM by oral glucose tolerance test (OGTT). In eight healthy volunteers (3 males; mean age, 41.8 y) wearing FGM sensors for 14 days, OGTT was performed during days 1-7 and days 8-14, and then both FGM-ISFG and PG were compared. Parkes error grid analysis indicated that all of 65 FGM-ISFG values were within Zone A (no effect on clinical action) and Zone B (little or no effect on clinical outcome). However, in OGTT, the mean FGM-ISFG was higher than the mean actual PG at 30, 60, and 90 minutes after loading (155.5 vs. 139.2 mg/dL, 166.2 vs. 139.2 mg/dL, 149.5 vs. 138.2 mg/dL, respectively; p<0.05). Moreover, the area under the curve of FGM-ISFG was also significantly larger than that of PG (17,626.2 vs. 15,195.0 min·mg/dL; p<0.05). In four of eight subjects, FGM-ISFG tended to be higher than PG in both OGTTs, and the greatest difference between the two values was 58 mg/dL. FGM is useful for glycemic control, whereas it is not appropriate to change therapeutic regimens based on the judgment of nocturnal hypoglycemia and postprandial hyperglycemia by FGM-ISFG. Careful attention is required for proper application of FGM.