Purpose: In this article, we report the results of a survey investigating post–coronavirus disease 2019 (COVID-19) syndrome in patients with type 2 diabetes mellitus and the impacts of vaccination on long-term manifestations. From February 2022 to April 2023, a survey of patients with type 2 diabetes and people without diabetes who were treated for a coronavirus infection was conducted in Kazakhstan.Methods: Participants were invited via social media to voluntarily participate in this study. A total of 417 surveys were included in this study, comprising 212 patients with type 2 diabetes and 205 without diabetes. We compared persistent complaints after recovery in patients with and without diabetes mellitus (DM), as well as vaccination status.Results: The results of this study on self-reported symptoms of prolonged COVID show that more than half of those infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Kazakhstan have at least one persistent symptom after recovery. Based on the list of prolonged COVID-19 symptoms reported by patients with type 2 DM (T2DM), exertional dyspnoea, fatigue, respiratory discomfort, headaches, and sleep disturbances are among the most common ongoing conditions, and in many cases last more than 3 months after COVID-19.Conclusion: Patients with T2DM experience more severe and prolonged symptoms than those without diabetes. Additionally, vaccination lowers COVID-19 hospitalization risk and decreases the need for adjusting hypoglycemic therapy, such as insulin treatment, after recovering from SARS-CoV-2 infection.