At the beginning of the coronavirus disease 2019 (COVID-19) outbreak in Daegu, the number of patients contracting COVID-19 has been skyrocketing [2], and strict social distancing, which is currently level-3 [3], was implemented to prevent transmission of infection [4]. Social distancing affects peoples’ health service use behavior [5], and the number of patients who attended the hospital during the COVID-19 outbreak was inevitably small compared to previous years. However, our study enrolled patients who had their glycosylated hemoglobin (HbA1c) levels measured during both Periods 1 (November 18 to February 17) and 2 (February 18 to May 17). Newly diagnosed patients with diabetes during Period 1 were diagnosed before COVID-19 outbreak, and newly diagnosed diabetic patients during Period 2 were not included in all cohorts (COVID-19 cohort and non-COVID-19 cohorts). Therefore, the number of newly diagnosed patients with diabetes was not influenced by the COVID-19 outbreak among cohorts and we believe it did not affect our research.

Nevertheless, your opinion is important and should be considered; a rapid decrease of HbA1c in newly diagnosed patients with diabetes might have affected the results of our study. HbA1c levels were markedly reduced in groups with baseline above 9.0%, which was consistent in all cohorts of our study. Peoples with newly diagnosed diabetes, especially those who visit tertiary hospitals, tend to show higher HbA1c levels; considering this, we agree with your opinion that the rapid decrease of HbA1c might be a consequence of enrollment of newly diagnosed patients with diabetes. However, we found that glycemic control worsened in patients with HbA1c <7% for all cohorts, and the increment of HbA1c levels was significantly higher in the COVID-19 cohort than in the non-COVID-19 cohorts. We believe that lifestyle changes due to social distancing might have caused this distinct increase in HbA1c levels in the COVID-19 cohort. We would like to thank Dr. Noh again for your comprehensive review and advice on our findings. The limitation of our study that you pointed out will be identified through follow-up researches to be conducted later.