Sasaki, Hironobu



School of Medicine, Center for Preventive Medicine (Shinanomachi)


Project Assistant Professor (Non-tenured)/Project Research Associate (Non-tenured)/Project Instructor (Non-tenured)

Academic Background 【 Display / hide

  • 2007.04

    Keio University

    University, Graduated

  • 2017.04

    Keio University

    Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • Bachelor of Medicine, Keio University, 2013.03

  • Doctor of Medicine, Keio University, Coursework, 2021.03

    Associations of birthweight and history of childhood obesity with beta cell mass in Japanese adults

Licenses and Qualifications 【 Display / hide

  • Board Certified Member of the Japanese Society of Internal Medicine, 2016.09

  • the Japan Medical Association (JMA)-certified Sports Medicine Physician, 2017.03

  • the Japan Medical Association (JMA)-certified Occupational Physician, 2019.07

  • Fellow of the Japan Diabetes Society, 2019.11

  • Approved Doctor by the Japan Association for Diabetes Education and Care, 2019.12

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Research Areas 【 Display / hide

  • Life Science / Metabolism and endocrinology (human islet research)

Research Keywords 【 Display / hide

  • Diabetes


Papers 【 Display / hide

  • Could the development of COVID-19 vaccine-induced type 1 diabetes be explained by a simple mechanism?

    Hironobu Sasaki, Arata Itoh, Hiroshi Itoh

    Diabetes & Metabolism (Elsevier BV)   2022.03

    Research paper (scientific journal), Joint Work, Lead author, Accepted,  ISSN  1262-3636

  • Dipeptidyl peptidase-4 inhibitors and beta cell mass in Japanese adults with type 2 diabetes

    Hironobu Sasaki, Yoshifumi Saisho, Hiroshi Itoh

    Endocrine Practice (Elsevier BV)   2022.02

    Research paper (scientific journal), Joint Work, Lead author, Accepted,  ISSN  1530-891X

  • Newly developed type 1 diabetes after coronavirus disease 2019 vaccination: A case report

    Hironobu Sasaki, Arata Itoh, Yasuhiro Watanabe, Yuya Nakajima, Yoshifumi Saisho, Junichiro Irie, Shu Meguro, Hiroshi Itoh

    Journal of Diabetes Investigation (John Wiley & Sons)   2022.01

    Research paper (scientific journal), Joint Work, Lead author, Accepted,  ISSN  2040-1116

     View Summary

    The vaccine for the coronavirus disease 2019 (COVID-19) has been reported to potentially cause or worsen diabetes. A 73-year-old Japanese woman received two doses of Moderna COVID-19 vaccine. Four weeks after the second vaccination, her glycemic control began to deteriorate, and 8 weeks after the second vaccination, the patient was diagnosed with new-onset type 1 diabetes that was strongly positive for autoantibodies and showed a disease-susceptible human leukocyte antigen haplotype, DRB1*04:05:01-DQB1*04:01:01. The glucagon stimulation test suggested an insulin-dependent state, and induction of intensive insulin therapy brought about fair glycemic control. The time period from the COVID-19 vaccination to the development of type 1 diabetes was relatively longer than to the onset or exacerbation of type 2 diabetes, as previously reported, suggesting the complicated immunological mechanisms for the destruction of β-cells associated with the vaccination. In recipients with the disease-susceptible haplotypes, one should be cautious about autoimmune responses for several months after the vaccination.

  • Changes in glycemic variability, gastric emptying and vascular endothelial function after switching from twice-daily to once-weekly exenatide in patients with type 2 diabetes: a subpopulation analysis of the twin-exenatide study

    Jun Inaishi, Yoshifumi Saisho, Yuusuke Watanabe, Tami Tsuchiya, Hironobu Sasaki, Tatsuhiro Masaoka, Hiroshi Itoh

    BMC Endocrine Disorders (BioMed Central)  22 ( 1 ) 20 2022.01

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    Background: We investigated the changes in blood glucose fluctuation, gastric emptying, and vascular endothelial function by switching from an exenatide twice-daily formulation (BID) to a once-weekly formulation (QW) since the evaluation of postprandial glucose excursion and glycemic variability (GV) by continuous glucose monitoring (CGM) after switching was lacking. Methods: Twenty-nine patients with type 2 diabetes treated with exenatide BID were included in this study and switched to exenatide QW for 24 weeks. GV assessed by CGM, gastric emptying (by 13 C-acetate breath test) and vascular endothelial function (by reactive hyperemia - peripheral arterial tonometry) were evaluated at baseline and 24 weeks after switching. Results: HbA1c decreased significantly from the baseline to week 24, while postprandial glucose levels after breakfast and dinner significantly increased (both P <0.05). However, the increases in GV indices were modest and not statistically significant at week 24. Vascular endothelial function was also not significantly changed after switching (P >0.05). Gastric emptying was significantly accelerated at week 24 (Tmax 83.4 ± 12.1 min vs. 58.2 ± 16.4 min) (P <0.001) and correlated with increased postprandial glucose levels after breakfast and dinner (both P <0.05). Conclusions: Despite the increase in postprandial glucose associated with accelerated gastric emptying after switching from exenatide BID to QW, change in GV was modest and no significant deterioration in vascular endothelial function was observed after switching. These results support the superiority of treatment with exenatide QW over exenatide BID in clinical practice; however, attention should be paid to the monitoring and management of postprandial glucose levels when selecting exenatide QW. Trial registration: Clinical trial registry number; UMIN000016390 and jRCTs031180320. Approval date of Registry and the Registration: December 12, 2014.

  • Revisiting regulators of human β-cell mass to achieve β-cell-centric approach toward type 2 diabetes

    Hironobu Sasaki, Yoshifumi Saisho, Jun Inaishi, Hiroshi Itoh

    Journal of the Endocrine Society (Oxford University Press)  5 ( 10 ) bvab128 2021.10

    Research paper (scientific journal), Joint Work, Lead author, Accepted

     View Summary

    Type 2 diabetes (T2DM) is characterized by insulin resistance and β-cell dysfunction. Since patients with T2DM have inadequate β-cell mass (BCM), and β-cell dysfunction worsens glycemic control and makes treatment difficult, therapeutic strategies to preserve and restore BCM are needed.In rodent models, obesity increases BCM about 3-fold, but the increase in BCM in humans is limited. Besides, obesity-induced changes in BCM may show racial differences between East Asians and Caucasians. Recently, the Developmental Origins of Health and Disease hypothesis, which states that the risk of developing non-communicable diseases including T2DM is influenced by the fetal environment, has been proposed. It is known in rodents that animals with low birthweight have reduced BCM through epigenetic modifications, making them more susceptible to diabetes in the future. Similarly, in humans, we revealed that individuals born with low birthweight have lower BCM in adulthood. Since β-cell replication is more frequently observed in the five years after birth, and β-cells are found to be more plastic in that period, a history of childhood obesity increases BCM. BCM in patients with T2DM is reduced by 20-65% compared with that in individuals without T2DM. However, since BCM starts to decrease from the stage of borderline diabetes, early intervention is essential for β-cell protection. In this review, we summarize the current knowledge on regulatory factors of human β-cell mass in health and diabetes, and propose the β-cell centric concept of diabetes to enhance a more pathophysiology-based treatment approach for T2DM.

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Awards 【 Display / hide

  • Medical Research Encouragement Prize

    2021.12, Tokyo Medical Association

    Type of Award: Award from publisher, newspaper, foundation, etc.

  • Young Investigator Award

    2021.06, the Japan Diabetes Society

    Type of Award: Award from Japanese society, conference, symposium, etc.

  • Clinical Investigator Award

    2020.10, the Hormone Station of Japan

    Type of Award: Award from publisher, newspaper, foundation, etc.


Committee Experiences 【 Display / hide

  • 2020

    Reviewer Board Member of the Japanese Society of Internal Medicine