Assessment of Serum Vitamin B12 and Vitamin D Levels among COVID-19-Vaccinated Hypertensive and Diabetic Population: A Cross-Sectional Study

Abstract

Introduction: Hypertension and type 2 diabetes mellitus (T2DM) are associated with altered micronutrient status and may influence metabolic responses following COVID-19 vaccination. This study compared serum vitamin B12 and vitamin D levels among COVID-19 vaccinated adults with hypertension, T2DM, and coexisting hypertension with T2DM.
Materials and Methods: This cross-sectional study included 240 adults who had received at least two doses of a COVID-19 vaccine. Participants were categorized into hypertension (n=86), T2DM (n=70), and hypertension with T2DM (n=84) groups. Fasting blood glucose (FBG), glycated haemoglobin (HbA1c), serum vitamin B12, and serum vitamin D concentrations were measured. Statistical analysis was performed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA).
Results: The mean age was highest in Group 3 (60.43±10.27 yr), followed by Group 1 (56.87±14.72 yr) and Group 2 (54.96±11.10 yr). FBG and HbA1c differed significantly among the study groups (P<0.001). Serum vitamin B12 concentrations were 313.29±234.69 pg/mL, 325.39±193.28 pg/mL, and 448.48±297.75 pg/mL in Groups 1, 2, and 3, respectively. Corresponding vitamin D concentrations were 33.51±18.61 ng/mL, 34.92±16.51 ng/mL, and 49.63±27.86 ng/mL, with significant differences across the groups (P=0.001 for vitamin B12 and P<0.001 for vitamin D).
Conclusions: Patients with both hypertension and T2DM demonstrated significantly elevated vitamin B12 and vitamin D levels following COVID-19 vaccination. These findings suggest possible immune-metabolic interactions, supporting routine micronutrient monitoring in individuals with chronic metabolic disorders.