Cardiovascular diseases (CVDs) remain the leading cause of global mortality, accounting for approximately one-third of all deaths worldwide. India is experiencing a rapid epidemiological transition with a rising burden of non-communicable diseases, particularly hypertension, diabetes mellitus, dyslipidemia, and obesity. Although conventional risk factors explain a substantial proportion of cardiovascular events, residual risk persists, prompting interest in novel and potentially modifiable factors.

Vitamin D, a fat-soluble secosteroid hormone, is traditionally recognized for its role in calcium and bone metabolism. It is synthesized in the skin upon exposure to ultraviolet B radiation and undergoes hepatic and renal hydroxylation to form its active metabolite. The discovery of vitamin D receptors in multiple tissues, including vascular smooth muscle cells, endothelial cells, cardiomyocytes, pancreatic beta cells, and immune cells, has expanded its role beyond skeletal health.

Vitamin D deficiency is a global health problem affecting nearly one billion individuals. Paradoxically, its prevalence is extremely high in tropical countries such as India, with reported rates ranging from 70% to 90%. Factors contributing to deficiency include limited sun exposure, darker skin pigmentation, air pollution, indoor lifestyles, dietary inadequacy, obesity, and lack of food fortification.

Several mechanisms link vitamin D deficiency to cardiometabolic disorders. Vitamin D suppresses renin gene expression, thereby regulating the renin–angiotensin–aldosterone system and blood pressure. Deficiency may lead to hypertension through increased vasoconstriction and sodium retention. Vitamin D also exerts anti-inflammatory effects by modulating cytokine production and inhibiting nuclear factor-kappa B signaling.

Insulin resistance and type 2 diabetes mellitus are major contributors to cardiovascular disease. Vitamin D influences insulin secretion and sensitivity, and low vitamin D levels have been associated with impaired glucose metabolism. Dyslipidemia, another key cardiovascular risk factor, has also been linked to vitamin D deficiency through effects on lipid synthesis and clearance.

Despite growing evidence, Indian studies comprehensively evaluating vitamin D deficiency in relation to multiple cardiometabolic risk markers are limited. The present study was therefore designed to assess the association between vitamin D status and cardiovascular risk markers in adults attending a tertiary care hospital.

This hospital-based cross-sectional analytical study was conducted in the Department of Medicine in collaboration with the Department of Biochemistry at a tertiary care center over a period of 24 months. Adults aged 18–65 years attending outpatient or inpatient services were recruited after obtaining written informed consent.

Participants with chronic kidney disease, chronic liver disease, malabsorption syndromes, malignancy, acute infections, autoimmune disorders, pregnancy, lactation, recent vitamin D supplementation, or long-term steroid therapy were excluded.

A pre-designed case record form was used to collect demographic details, clinical history, and lifestyle factors. Anthropometric measurements including height, weight, and BMI were recorded. Blood pressure was measured using a standard mercury sphygmomanometer.

Venous blood samples were collected after an overnight fast. Serum 25-hydroxyvitamin D was measured using chemiluminescent immunoassay. Fasting blood glucose was estimated using the glucose oxidase-peroxidase method. HbA1c was measured using standardized methods. Lipid profile parameters were estimated using enzymatic methods, and LDL-cholesterol was calculated using Friedewald’s formula. hs-CRP was measured using high-sensitivity immunoturbidimetric assay.

Statistical analysis was performed using SPSS version 26. Continuous variables were expressed as mean ± standard deviation. Group comparisons were performed using Student’s t-test and ANOVA. Correlations were assessed using Pearson’s correlation coefficient. A p-value <0.05 was considered statistically significant

Of the 200 participants, 56% were males and 44% were females. Vitamin D deficiency was observed in 64% of participants, while only 13% had sufficient vitamin D levels.

Vitamin D deficient individuals had significantly higher fasting blood glucose and HbA1c levels compared to vitamin D sufficient participants (p < 0.001). Lipid profile analysis revealed significantly higher total cholesterol, LDL-cholesterol, triglycerides, and lower HDL-cholesterol in the deficient group.

Blood pressure parameters and BMI were significantly higher in vitamin D deficient individuals. hs-CRP levels were markedly elevated in the deficient group, indicating increased systemic inflammation.

Serum vitamin D levels showed significant negative correlations with fasting blood glucose, LDL-cholesterol, systolic blood pressure, and hs-CRP (all p < 0.001).

Table 1. Baseline Demographic Characteristics of Study Participants (n = 200)

The study population showed a slight male predominance with the majority belonging to the 31–45 year age group. Most participants were from urban areas.

Table 2. Distribution of Participants According to Vitamin D Status

Nearly two-thirds of participants were vitamin D deficient, highlighting widespread hypovitaminosis D.

Table 3. Mean Serum Vitamin D Levels by Category

Mean vitamin D levels differed significantly across categories, confirming accurate classification.

Table 4. Comparison of Glycemic Parameters Between Vitamin D Deficient and Sufficient Groups

Vitamin D deficiency was associated with significantly poorer glycemic control.

Table 5. Comparison of Lipid Profile Parameters

                               Vitamin D deficient individuals exhibited a significantly more atherogenic lipid profile.

Table 6. Comparison of Blood Pressure and BMI

Vitamin D deficiency was significantly associated with higher blood pressure and increased BMI.

Table 7. Comparison of Inflammatory Marker (hs-CRP)

Vitamin D deficient participants had significantly elevated systemic inflammation.

Table 8. Prevalence of Cardiometabolic Risk Factors

Clustering of cardiometabolic risk factors was markedly higher in vitamin D deficient individuals.

Table 9. Correlation Between Serum Vitamin D Levels and Cardiometabolic Parameters

Serum vitamin D showed significant negative correlations with major cardiovascular risk markers.

Table 10. Overall Cardiovascular Risk Stratification

Nearly half of vitamin D deficient participants were classified as high cardiovascular risk

The present study demonstrates a high prevalence of vitamin D deficiency and its significant association with adverse cardiometabolic risk markers. The findings are consistent with previous Indian and international studies.

The observed association between vitamin D deficiency and poor glycemic control may be explained by impaired insulin secretion and increased insulin resistance. Dyslipidemia observed in vitamin D deficient individuals may result from altered lipid metabolism and increased inflammatory activity.

Hypertension observed in vitamin D deficient participants supports the role of vitamin D in renin–angiotensin system regulation. Elevated hs-CRP levels highlight the contribution of vitamin D deficiency to systemic inflammation and atherosclerosis.

The cross-sectional design limits causal inference; however, the strong associations observed underscore the potential role of vitamin D deficiency as a modifiable cardiovascular risk factor.

Vitamin D deficiency is highly prevalent and significantly associated with adverse cardiometabolic risk markers. Screening and targeted correction of vitamin D deficiency may serve as an effective strategy for cardiovascular risk reduction.

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