Vitamin D is a fat-soluble vitamin which plays a vital role in humans’ body. Its deficiency affects almost half of the population worldwide¹. According to the international diabetes federation, the number of diabetes patients is expected to increase from 415 million to 642 million by 2040. India will become the capital of diabetes till 2040.^2,3 It is high in diabetic patients which confirm that the disease is a secondary result of autoimmune reaction.⁴ The committee of Food and Nutrition Board (FNB) specified vitamin D deficiency at concentrations less than 30 nmol/L (12 ng/mL); insufficiency at 30 to 50 nmol/L (12–20 ng/mL), and sufficient at 50 nmol/L (20 ng/mL) or more  3.⁵ Some studies linked inadequate levels of vitamin D to other conditions such as CVD, hypertension, autoimmune diseases, cancer, and insulin resistance, which related to type 2 diabetes, and its complications^6,7 .Recent evidence from human and animal research have shown the relationship between vitamin D status and glucose homeostasis as well as impaired insulin sensitivity. Many epidemiological studies showed that vitamin D deficiency was common in diabetes subjects, while some trials indicated that 25-hydroxyvitamin D (25(OH)D) levels had no influence on the diabetes.⁸ Type 2 diabetes mellitus (T2DM) is a heterogeneous metabolic disorder which is characterized by impairment of insulin secretion, insulin action, or both. It involves dysfunction of pancreatic beta cells , systemic inflammation, and elevated blood glucose levels ⁹. T2DM is considered as the most prevalent type of diabetes, affecting 90-95% of all diabetic patients . Diabetic complications are classified to microvascular complications, which related to damage to small blood vessels e.g in nervous system (neuropathy), renal system (nephropathy) and eye (retinopathy) and macrovascular complications due to damage to the arteries which involve peripheral vascular disease , coronary artery disease, and  cerebrovascular disease.Previous studies reported a relationship between vitamin D and T2DM, and there is evidence that vitamin D contributes to the onset of diabetes ^10,11. Several studies connected vitamin D deficiency to the occurrence of T2DM complications.After extensive research in literature we do not find any study on the status of vitamin D3 in patients of type-2 diabetes mellitus¹². Therefore, this study is planned to evaluate the status of vitamin D3 in patients of type-2 DM.

AIM

To assess the vitamin D3 status and identify the associated risk factors influencing vitamin D3 deficiency in patients with Type 2 Diabetes Mellitus.

The present study was an observational cross-sectional study conducted in the Department of Medicine, Sardar Patel Medical College and Associated Group of P.B.M. Hospitals, Bikaner, Rajasthan, over a period of six months from 1st October 2023 to 31st March 2024. Convenience random sampling was used for the selection of study participants. The study population comprised all patients with Type 2 Diabetes Mellitus attending the Medicine Outpatient Department (OPD) during the study period. Patients aged between 20 and 70 years, diagnosed with Type 2 Diabetes Mellitus, not receiving vitamin D3 supplementation in any form, and willing to provide informed consent were included in the study. Patients who did not provide consent, those suffering from diseases other than diabetes mellitus and its complications, and those who were currently taking or had taken vitamin D3 supplementation in any form during the preceding six months were excluded from the study.

Table 1 – Distribution of vitamin D3 status in DM

Vitamin D3 >30 ng/ml: 20 males (52.63%) and 18 females (47.37%) had sufficient vitamin D levels.38 out of 75 patients (50.67%) had vitamin D sufficiency. Vitamin D3 <30 ng/ml: 20 males (50.05%) and 17 females (45.95%) had insufficient or deficient vitamin D levels.

Table 2– Correlation of vitamin D3 deficiency with residence

In table 3, rural population of DM group (n=75), 3 patients have vitamin D deficiency (<20 ng/ml), 1 patient has vitamin D insufficiency (20–30 ng/ml), and 10 patients have sufficient vitamin D levels (>30 ng/ml). The mean vitamin D level is

34.38 ± 14.66 ng/ml.

Table 3: Correlation of vitamin D3 status in tobacco chewer and smoker patients and alcohol patients

Smokers in DM group, 1 patient has vitamin D deficiency (<20 ng/ml), 0 patients have vitamin D insufficiency (20–30 ng/ml), and 2 patients have sufficient vitamin D levels (>30 ng/ml). The mean vitamin D level is 27.05 ± 11.04 ng/ml.Non smokers in DM group, 23 patients have vitamin D deficiency, 13 have insufficiency, and 36 have sufficient levels. The mean vitamin D level is 29.83 ± 14.77 ng/ml.Tobacco user in the DM group, 2 patients have vitamin D deficiency, 0 have insufficiency, and 6 have sufficient levels. The mean vitamin D level is 36.19 ± 16.48 ng/ml.Non tobacco users in DM group, 22 patients have vitamin D deficiency, 13 have insufficiency, and 32 have sufficient levels. The mean vitamin D level is 28.95 ± 14.22 ng/ml..Alcohol users in DM group, 2 patients have vitamin D deficiency (<20 ng/ml), 1 patient has vitamin D insufficiency (20–30 ng/ml), and 4 patients have sufficient vitamin D levels (>30 ng/ml). The mean vitamin D level is 29.53 ± 14.83 ng/ml.Non alcoholic users in DM group, 22 patients have vitamin D deficiency, 12 have insufficiency, and 34 have sufficient levels. The mean vitamin D level is 31.65 ± 12.56 ng/ml.

Table 4:Correlation of vitamin D3status in DM  with Socioeconomic status

Upper: 9 individuals were vitamin D deficient, 6 were vitamin D insufficient, and 11 had sufficient levels. The mean ± SD vitamin D level was 27.05 ± 14.10 ng/ml.  

Middle: 13 individuals were vitamin D deficient, 6 were vitamin D insufficient, and 22 had sufficient levels. The mean ± SD vitamin D level was 31.16 ± 15.36 ng/ml.  

Lower: 2 individuals were vitamin D deficient, 1 was vitamin D insufficient, and 5 had sufficient levels. The mean ± SD vitamin D level was 31.06 ± 10.96 ng/ml.

We found high prevalence of vitamin D3 low status in patients of diabetes mellitus (49.33%, mean 29.72±14.77) (P<0.00001). Low level of vitamin D3 has been reported in diabetes mellitus, Yildiz BA et al (2021)13 reported vitamin D deficiency in 63.8% diabetic patients. Similar study Salih YA et al (2021)14 done in age more than 25 years old and Type 2DM on treatment either with diet only or with diet and oral anti–diabetic drugs found that a significant difference in vitamin D levels among cases and controls (p < 0.001), vitamin D level was lower among females compared to males, p< 0.001 and those living in urban areas compared to rural areas (p< 0.001).They also found significant effect of BMI and dyslipidemia on vitamin D levels among diabetics, (p values <0.002 and <0.001 respectively).It is thought that insulin resistance, involved in the pathogenesis of type 2 DM, is reduced by the anti-inflammatory and immunomodulatory activity of vitamin D. Also, vitamin D may predict the progression of insulin resistance to type 2 DM Vitamin D acts on insulin receptor gene regulation through calcium metabolism and vitamin D receptors. It has been shown that adequate levels of vitamin D are effective in the release of insulin from pancreatic beta cells. patients. We found statistically significant low vitamin D3 status in diabetes mellitus belonging to urban residence and compared to rural residence. Similarly Pradeep AP et al (2023)15 also found that vitamin D deficiency was more than 3 times higher among both urban men and women population as compared to their rural counterparts. The urban propensity for Vitamin D deficiency may be related to increased indoor lifestyle and reduced sunlight exposure and food habits that contribute to low dietary calcium and Vitamin D intake. Severe air pollution that blocks sunlight in urban areas may also contribute to the low vitamin D levels. In our study, we found that low level of vitamin D3 in diabetes mellitus irrespective of their consumption of smoking and nonsmoking. Lange NE et al (2012)16 in a cross sectional analysis using a multivariable model adjusted for age, height, pack-years, BMI, season, and smoking status, there were significant interactions (P < 0.02) between VDD and pack-years of smoking for all spirometric measures of lung function (FEV1, P ¼ 0.007; FVC, P ¼ 0.02; FEV1/FVC,P ¼ 0.004). Effects were also significant (P < 0.01) when analyzed by smoking status. We also found a significant correlation of tobacco chewers with low levels of vitamin D3 in diabetes mellitus as compared to nontobacco chewers (p<0.0001). Moreover, active smoking of adults was also related to increased risk of VD inadequacy. We also found a negative correlation of alcohol with low levels of vitamin D3 in diabetes mellitus . Similarly Verma AK et al (2023)17 found that patients having higher alcohol consumption, there is more chance of having vitamin D deficiency and insufficiency than the patient’s nonalcoholic. By their study possible explanations of low level of vitamin D deficiency in alcoholic patients due to decreased vitamin D hydroxylation and inadequate sun exposure, insufficient food intake, jaundice related deterioration of vitamin synthesis on the skin, and decreased vitamin D absorption caused by intestinal oedema secondary to portal hypertension or due to cholestasis-induced bile salt disruption. In our study, we found that patients belonging to the upper socioeconomic class have more vitamin D deficiency in diabetes mellitus . Scully H et al (2022)18 observed that vitamin D deficiency (<30 nmol/l) was prevalent affecting 23% in upper class socioeconomic status (P <0.03).This may be because of life style like less exposure to sun light, less outdoor activity, reduce physical activity and greater obesity prevalence. On multiple linear regressions analysis, we found that low levels of vitamin D3 in diabetes mellitus correlated with increasing age, female gender, urban residence, and high socioeconomic status .

Vitamin D3 deficiency was highly prevalent among patients with Type 2 Diabetes Mellitus. Low vitamin D3 status was significantly associated with urban residence, tobacco chewing, alcohol consumption, and higher socioeconomic status. Multivariate analysis demonstrated that increasing age, female gender, urban residence, and higher socioeconomic status were independent predictors of low vitamin D3 levels. These findings highlight the need for routine assessment of vitamin D3 status in diabetic patients, particularly among those with identified risk factors, to facilitate early intervention and potentially improve metabolic outcomes.

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