ABSTRACT
The study was aimed to investigate the seasonal variation of hemoglobin A1c (HbA1c) in adults with type 1 diabetes (T1D) and the impact of coronavirus disease 2019 (COVID-19) by comparing 2019 and 2021 data and differences in treatment modes. This was a single-center retrospective observational study including 52 adult patients with T1D who regularly visited hospital in 2019 and 2021. Twenty-five patients used multiple daily injections (MDI)/self-measurement of blood glucose (SMBG), 16 used MDI/intermittently scanned continuous glucose monitoring (isCGM), 9 used sensor-augmented pump (SAP), and 2 used continuous subcutaneous insulin infusion (CSII)/isCGM. The mean HbA1c level was calculated for each month. The correlation between monthly means of temperature and HbA1c was investigated. Similar analyses were performed for the MDI/SMBG, MDI/isCGM, and SAP + CSII/isCGM groups. HbA1c levels in 2019 decreased in summer and increased in winter and showed a significant negative correlation with temperature (r = -0.652, p = 0.022). However, HbA1c in 2021 showed no seasonal variation and no correlation with temperature (r = -0.134, p = 0.678) and tended to decline after the three emergency declarations. HbA1c in the MDI/SMBG group showed the same trend as the whole group in 2019 and 2021. However, the effect of seasonal variation in HbA1c was lower in the MDI/isCGM group and the lowest in the SAP + CSII/isCGM group in 2019. The impact of emergency declaration on HbA1c level was small for the MDI/isCGM group and smaller for the SAP + CSII/isCGM group in 2021. The COVID-19 pandemic has affected the seasonal variation of HbA1c levels in T1D; the variation differed according to the treatment mode.
ABSTRACT
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 ß-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.