The Impact of COVID-19 Vaccination on Bulgarian Patients with Uncomplicated Type 2 Diabetes Mellitus as the Only Chronic Condition

Abstract

Abstract Objective: This retrospective study aimed to investigate the impact of COVID-19 vaccination on Bulgarian patient cohorts with uncomplicated diabetes mellitus type 2 as the only documented chronic comorbidity. We conducted a comparison of fully vaccinated and non-vaccinated populations, considering gender, age groups and vaccine type, across ambulatory, hospital, and ICU settings. Design: Between March 2020 and June 2022, a comprehensive retrospective analysis was conducted on a national level, utilizing data from the Ministry of Health of the Republic of Bulgaria database obtained after a formal written request. The study included a total of 1,126,946 confirmed COVID-19 patients. Results: Among the 1,126,946 confirmed COVID-19 patients, 3,792 individuals (0.33% of the total confirmed cases) had diabetes mellitus as a single chronic condition. Among the 247,441 hospitalized COVID-19 cases, 1,382 patients (0.56% of the total) had type 2 diabetes mellitus. Notably, the majority of patients requiring hospitalization due to supplemental oxygen requirement were unvaccinated women aged between 60 and 69, accounting for 240 patients. The highest mortality rates were observed in both unvaccinated men and women aged between 70 and 79, with 88 patients in each group. Statistical analysis revealed significant findings in favor of reduced rates of ambulatory care [OR = 0.76 (95% CI 0.6471 to 0.8891); p = 0.0006], intensive care admission [OR = 0.38 (95% CI 0.2698 to 0.5282); p < 0.0001], in-hospital mortality [OR = 0.18 (95% CI 0.0864 to 0.3604); p < 0.0001], and ICU-related mortality [OR = 0.17 (95% CI 0.0893 to 0.3436); p < 0.0001]. The vaccinated cohorts who received BNT162b2 demonstrated the lowest observed death rates, with 9 deaths out of 485 individuals (1.8%) across all age groups. Conclusion: In conclusion, this retrospective analysis indicates reduced mortality in patients with uncomplicated type II diabetes mellitus who received vaccination against SARS-CoV-2. Vaccinated individuals also showed significant reduction in ICU admissions.