Only a limited number of investigations have focused on how the coexistence of type 2 diabetes mellitus (T2DM) and periodontitis (PD) influences serum Vitamin D concentration, especially in developing nations such as India. This aspect requires more scientific attention. The goal of this study was to explore how serum Vitamin D values relate to periodontal disease in individuals affected by T2DM, and to determine whether socioeconomic and demographic factors have any bearing on Vitamin D concentration or the degree of periodontal breakdown in these patients. This cross-sectional hospital-based analysis gathered participants’ medical, dental, and nutritional records and assessed their socioeconomic status (SES). Clinical indices such as the plaque index (PI), gingival index (GI), gingival bleeding sites, probing pocket depth (PPD), and clinical attachment level (CAL) were evaluated across three groups: 1. Individuals with generalized Stage III Grade B PD and T2DM (n = 35); 2. Patients with generalized Stage III Grade B PD only (n = 35); Healthy control participants (n = 35). Laboratory analysis included testing for serum 25-hydroxyvitamin D (25[OH]D) and hemoglobin A1C (HbA1c) levels. Comparisons of periodontal and biochemical markers among the groups were made using one-way ANOVA. Correlations between 25(OH)D, clinical variables, and SES were determined through Pearson’s correlation and linear regression models. Participants with Stage III Grade B PD along with T2DM exhibited the lowest mean 25(OH)D concentration (13.54 ± 3.31 ng/mL). A strong negative relationship (P < 0.01) was found between serum 25(OH)D levels and periodontal indices — PI (−0.442), PPD (−0.474), CAL (−0.459), gingival bleeding (−0.354), and GI (−0.346). Regression outcomes revealed that increased periodontal damage (PI, GI, PPD, CAL) and higher HbA1c were linked with diminished 25(OH)D values. Conversely, Vitamin D status showed no meaningful correlation with socioeconomic or demographic characteristics. The findings indicate that Vitamin D levels decline when PD and T2DM coexist or even when PD occurs alone. However, SES did not significantly influence Vitamin D concentration in either group.
