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Status of glycemic excursions and hypoglycemia in patients with type 1 diabetes 2 months after first initiation of intermittently scanned continuous glucose monitoring: a pilot study



To investigate glycemic excursions and changes in time in hypoglycemia (hyT) in Japanese type 1 diabetes (T1D) patients 2 months after the first initiation of intermittently scanned continuous glucose monitoring (isCGM).


We enrolled 15 adult T1D patients on insulin therapy to evaluate changes in the parameters for glycemic excursions 2 months after initiating isCGM by using the Wilcoxon signed-rank test. Binomial logistic regression analyses were also used to identify predictors of hypoglycemia.


A total of 14 patients were available for analysis. Median HbA1c decreased significantly from 7.6% (interquartile range, 6.9–8.3%) to 7.2% (6.7–7.8%) (P = 0.047). Mean glucose, standard deviation of glucose, time in range, and time above range were not significantly different from baseline, while time below range (from 2.2 [1.0–6.9] to 5.0 [2.0–10.8]%; P = 0.016), hyT (from 26.8 [14.5–75.5] to 56.8 [21.7–110.9] min/day; P = 0.030), and time in severe hypoglycemia (shT, from 4.3 [0.0–8.9] to 11.0 [0.0–24.3] min/day; P = 0.022) increased significantly. Additionally, shT increased significantly only during daytime. The factor associated with hyT was found to be the reduction in total insulin dose after 2 months.


In T1D patients with a median HbA1c of 7.6%, HbA1c was significantly decreased 2 months after initiating isCGM, while hyT increased, particularly during daytime. Study results suggest that a reduction in the total insulin dose of about 0.10 U/kg may be required in some cases. These findings need to be taken into account when initiating isCGM.

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The authors wish to extend their heartfelt thanks to all patients for their participation in the study.


This work was supported in part by a grant from the Ministry of Health, Labor and Welfare of Japan (H28-Cardiology etc., General-006). The funders had no role in study design, data collection/analysis, decision to publish, or preparation of this manuscript.

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Authors and Affiliations



RN contributed to the study design. YS and HT contributed to the data collection. YS, HT, and RN contributed to the data analysis. YS, HT, and RN contributed to the writing, reviewing, and editing of the manuscript.

Corresponding author

Correspondence to Yuka Suganuma.

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Conflict of interest

The authors of this manuscript have the following competing interests: RN received honoraria from Sanofi Co., Ltd., Japan Medtronic Co., Ltd., Nippon Boehringer Ingelheim Co., Ltd., Takeda Pharmaceutical Company Limited, Kissei Pharmaceutical Co., Ltd., Novartis Pharma Co., Ltd., Eli Lilly Japan Co., Ltd., Novo Nordisk Pharma Ltd., MSD and Astellas Pharma Inc, and subsidies or donations from Taisho Pharmaceutical Co., Ltd, Ono Pharmaceutical Co., Ltd, Takeda Pharmaceutical Company Limited and Nippon Boehringer Ingelheim Co., Ltd. TH received honoraria from Eli Lilly Japan Co., Ltd. YS have no conflicts of interest to declare.

Ethical approval

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (the Ethics Committee of the Jikei University School of Medicine (approval number 27–091(7976), approved September 7, 2015) and with the Helsinki Declaration of 1964 and its later versions.

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Written informed consent was obtained from all patients.

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Suganuma, Y., Takahashi, H. & Nishimura, R. Status of glycemic excursions and hypoglycemia in patients with type 1 diabetes 2 months after first initiation of intermittently scanned continuous glucose monitoring: a pilot study. Diabetol Int (2022).

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  • Type 1 diabetes
  • isCGM
  • Time in hypoglycemia
  • Time in severe hypoglycemia
  • Time below range