Background:The coronavirus disease 2019 (COVID-19) pandemic has rapidly transformed health care delivery into telehealth visits. Attending regular medical appointments are critical to prevent or delay diabetes-related complications. Although telehealth visits have addressed some barriers to in-person visits, appointment no-shows are still noted in the telehealth setting. It is not completely clear how the predictors of appointment no-shows differ between in-person and telehealth visits in diabetes care.Objective:This retrospective study examined if predictors of appointment no-shows differ (1) between pre-COVID (January 1, 2019–March 22, 2020) and COVID (March 23, 2020–December 31, 2020) periods and (2) by health care delivery modes (in-person or telehealth visits) during COVID among adults with type 2 diabetes mellitus (T2DM).Methods:We used electronic health records between January 1, 2019 and December 31, 2020 across four diabetes clinics in a tertiary academic hospital in Baltimore, Maryland. Appointments marked as completed or no-show by established adults with T2DM were included in the analyses.Results:Among 7,276 appointments made by 2,235 patients, overall appointment no-show was 14.99%. Being older and White were protective against appointment no-shows in both unadjusted and adjusted models during both time periods. The interaction terms of COVID periods (i.e., pre-COVID vs. COVID) were significant for when glycated hemoglobin drawn before this visit and for missing body mass index. Telehealth visits during COVID decreased more half of the odds of appointment no-shows.Conclusions:In the context of diabetes care, the implementation of telehealth reduced appointment no-shows. Future studies are needed to address social determinants of health, including access to internet access, to further reduce health disparities among adults with T2DM.