The coronavirus disease 2019 (COVID-19) pandemic instigated major changes in care delivery, but our understanding of how the rapid transition from in-person to telehealth encounters affected the care of patients with chronic conditions such as type 2 diabetes remains incomplete. This study examined changes in primary care encounters, A1C testing rates, and the likelihood of meeting A1C guidelines before and during the first 9 months of the COVID-19 pandemic in a large health care system. It found significant decreases in utilization and testing rates and the likelihood of meeting A1C guidelines, primarily driven by missing A1C tests. Patients who had all telehealth encounters or no encounters, who identified as racial or ethnic minorities, or had Medicaid or no insurance were significantly more likely to miss A1C tests.