Poor vitamin D status may contribute to high risk for insulin resistance, obesity, and cardiovascular disease in Asian Indians

Assessment of insulin resistance in patients with primary hyperparathyroidism before and after Parathyroidectomy

Background

Primary hyperparathyroidism (PHPT) can lead to renal and skeletal disorders, as well as insulin resistance and impaired glucose metabolism. The current study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with PHPT.

Materials and Methods

The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy who were referred to the endocrinology clinics of Mashhad University of Medical Sciences. Thereafter, the demographic characteristics of the patients were recorded. Blood tests, including haemoglobin A1c (HbA1c), fasting blood glucose (FBG) and insulin levels, were assessed one week before and three months after the surgery. The insulin resistance score (HOMA‐IR) was calculated and compared using the relevant formula.

Results

A total of 65 participants with a mean age of 45.44 ± 9.59 years were included in the current study. In one‐month postoperative tests, mean scores of FBG (p < .05), insulin level (p < .05) and HbA1c (p < .05) were significantly reduced. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery.

Conclusion

According to our findings, parathyroidectomy can be effective in the reduction of insulin resistance and corresponding complications in patients with PHPT in the present short‐term study. However, it has yet to be confirmed as a treatment method for insulin resistance in these patients. Future long‐term studies are required to be done to investigate the effect of parathyroidectomy on insulin resistance.

The present study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with primary hyperparathyroidism (PHPT). The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy. Demographic characteristics of the patients were recorded. Blood tests, including fasting blood sugar (FBS), haemoglobin A1c (HbA1c) and insulin levels, were assessed one week before and three months after the surgery. The Homeostatic Model Assessment for Insulin Resistance (HOMA‐IR index) was calculated. In one‐month postoperative tests, mean scores of FBS (p < .05), insulin level (p < .05) and HbA1c (p < 0.05) were significantly reduced compared to these variables prior to the surgery. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery. As evidenced by the results of the present study, parathyroidectomy can be effective in reducing insulin resistance and its complications in patients with primary hyperparathyroidism (PHPT).

Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome

The aim of this study is to determine the relationships of vitamin D with diabetes, insulin resistance obesity, and metabolic syndrome. Intra cellular vitamin D receptors and the 1-α hydroxylase enzyme are distributed ubiquitously in all tissues suggesting a multitude of functions of vitamin D. It plays an indirect but an important role in carbohydrate and lipid metabolism as reflected by its association with type 2 diabetes (T2D), metabolic syndrome, insulin secretion, insulin resistance, polycystic ovarian syndrome, and obesity. Peer-reviewed papers, related to the topic were extracted using key words, from PubMed, Medline, and other research databases. Correlations of vitamin D with diabetes, insulin resistance and metabolic syndrome were examined for this evidence-based review. In addition to the well-studied musculoskeletal effects, vitamin D decreases the insulin resistance, severity of T2D, prediabetes, metabolic syndrome, inflammation, and autoimmunity. Vitamin D exerts autocrine and paracrine effects such as direct intra-cellular effects via its receptors and the local production of 1,25(OH)₂D₃, especially in muscle and pancreatic β-cells. It also regulates calcium homeostasis and calcium flux through cell membranes, and activation of a cascade of key enzymes and cofactors associated with metabolic pathways. Cross-sectional, observational, and ecological studies reported inverse correlations between vitamin D status with hyperglycemia and glycemic control in patients with T2D, decrease the rate of conversion of prediabetes to diabetes, and obesity. However, no firm conclusions can be drawn from current studies, because (A) studies were underpowered; (B) few were designed for glycemic outcomes, (C) the minimum (or median) serum 25(OH) D levels achieved are not measured or reported; (D) most did not report the use of diabetes medications; (E) some trials used too little (F) others used too large, unphysiological and infrequent doses of vitamin D; and (G) relative paucity of rigorous clinical data on the effects of vitamin D sufficiency on non-calcium endpoints. Although a large number of observational studies support improving T2D, insulin resistance, obesity, and metabolic syndrome with vitamin D adequacy, there is a lack of conclusive evidence from randomized control clinical trials that, these disorders are prevented following optimization of serum levels of 25(OH)D. However, none of the currently conducted clinical studies would resolve these issues. Thus, specifically designed, new clinical studies are needed to be conducted in well-defined populations, following normalizing the serum vitamin D levels in vitamin D deficient prediabetes subjects, to test the hypothesis that hypovitaminosis D worsens these disorders and correction would alleviate it.

Non-musculoskeletal benefits of vitamin D

The aim of this study is to determine and critically evaluate the plausible relationships of vitamin D with extra-skeletal tissues in humans. Severe vitamin D deficiency results in rickets in children and osteomalacia in adults; these beneficial effects in the musculoskeletal system and certain physiological functions are well understood. Nevertheless, mounting reports support additional beneficial effects of vitamin D, outside the musculoskeletal system. This review explores the recent advances in knowledge about the non-skeletal effects of vitamin D. Peer-reviewed papers were extracted from research databases using key words, to assess correlations between vitamin D and extra-skeletal diseases and conditions. As per the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA); general interpretations of results are included; taking into consideration the broader evidence and implications. This review summarizes current knowledge of the effects of vitamin D status on extra-skeletal tissues with special attention given to relationships between vitamin D status and various diseases commonly affecting adults; the effects of intervention with vitamin D and exposure to sunlight. Evidence suggests that vitamin D facilitates the regulation of blood pressure; and cardiac; endothelial; and smooth muscle cell functions; playing an important role in cardiovascular protection. In addition; 1,25(OH)₂D improves immunity; subdues inflammation; and reduces the incidence and severity of common cancers; autoimmune diseases and infectious diseases. Almost all adequately powered; epidemiological and biological studies that use; adequate doses of vitamin D supplementation in D-deficient populations have reported favorable outcomes. These studies have concluded that optimizing 25(OH)D status improves the functionality of bodily systems; reduces comorbidities; improves the quality of life; and increases survival. Although accumulating evidence supports biological associations of vitamin D sufficiency with improved physical and mental functions; no definitive evidence exists from well-designed; statistically powered; randomized controlled clinical trials. Nevertheless, most studies point to significant protective effects of vitamin D in humans when the minimum 25(OH)D serum level exceeds 30ng/mL and is maintained throughout the year.

Vitamin D level and its association with adiposity among multi-ethnic adults in Kuala Lumpur, Malaysia: a cross sectional study

Background

Vitamin D deficiency is highly prevalent in both temperate as well as tropical countries. Obesity is one of the factors contributing to vitamin D deficiency. As our country has a high prevalence of overweight and obesity, we aimed to study serum 25-hydroxyvitamin D (25(OH)D) level and its association with adiposity using various adiposity indicators; and to study other risk factors that affect serum 25(OH)D level among multi-ethnic adults in Kuala Lumpur, Malaysia.

Methods

This was a cross sectional study conducted with a multistage sampling. All permanent teachers working in government secondary schools in Kuala Lumpur were invited for the study. The data collection included serum 25(OH)D, Parathyroid Hormone (PTH), body fat percentage, waist circumference, body mass index (BMI) and blood pressure. Demographic characteristics, sun avoidance, sun exposure and physical activity were enquired from the participants using a self-administered questionnaire. The data was analyzed using a complex sample analysis.

Results

A total of 858 participants were recruited. Majority of them were Malays, females and had tertiary education. The overall prevalence of vitamin D deficiency (<20 ng/ml) was 67.4 %. Indian participants (80.9 %) had the highest proportion of vitamin D deficiency, followed by Malays (75.6 %), others (44.9 %) and Chinese (25.1 %). There was a significant negative association between serum 25(OH)D level with BMI (β = −0.23) and body fat percentage (β = −0.14). In the multivariate linear regression analysis, Malays, Indians and females (p < 0.001); higher BMI and larger waist circumference (p < 0.05) were significantly associated with lower serum 25(OH)D level. The full model explained 32.8 % of the variation between participants in the serum 25(OH)D level. The two most influential factors affecting serum 25(OH)D level were ethnicity and gender.

Conclusions

The prevalence of vitamin D deficiency among our participants was high. Adiposity was associated with serum 25(OH)D level. Skin pigmentation and gender based behaviours were more dominant in contributing to serum 25(OH)D level. Health education should be targeted in weight management, gender based behaviours on sun exposure, as skin pigmentation is non-modifiable.

Effect of vitamin D supplementation on cardiometabolic risks and health-related quality of life among urban premenopausal women in a tropical country--a randomized controlled trial

Background

Many observational studies linked vitamin D to cardiometabolic risks besides its pivotal role in musculoskeletal diseases, but evidence from trials is lacking and inconsistent.

Aim

To determine whether Vitamin D supplementation in urban premenopausal women with vitamin D deficiency can improve cardiometabolic risks and health-related quality of life (HRQOL).

Design

A double-blind randomized controlled trial was conducted in Kuala Lumpur, Malaysia. A total of 192 vitamin D deficient (<50 nmol/l) premenopausal women were randomized to receive either vitamin D 50,000 IU or placebo once a week for 2 months and then monthly for 10 months. Primary outcomes were serum 25(OH)D, serum lipid profiles, blood pressure and HOMA-IR measured at baseline, 6 months and 12 months. HRQOL was assessed with SF-36 at baseline and 12 months.

Results

Ninety three and ninety-nine women were randomised into intervention and placebo groups respectively. After 12 months, there were significant differences in the serum 25(OH)D concentration (mean difference: 49.54; 95% CI: 43.94 to 55.14) nmol/l) and PTH levels (mean difference: −1.02; 95% CI: −1.67 to −0.38 pmol/l) in the intervention group compared to placebo group. There was significant difference between treatment group in both serum 25(OH)D and PTH. There was no effect of supplementation on HOMA-IR, serum lipid profiles and blood pressure (all p>0.05) between two groups. There was a small but significant improvement in HRQOL in the components of vitality (mean difference: 5.041; 95% CI: 0.709 to 9.374) and mental component score (mean difference: 2.951; 95% CI: 0.573 to 5.329) in the intervention group compared to placebo group.

Conclusion

Large and less frequent dosage vitamin D supplementation was safe and effective in the achievement of vitamin D sufficiency. However, there was no improvement in measured cardiometabolic risk factors in premenopausal women. Conversely vitamin D supplementation improves some components of HRQOL.

Trial Registration

Australian New Zealand Clinical Trial Registry ACTRN12612000452897

Independent associations of low 25 hydroxy vitamin D and high parathyroid hormonal levels with nonalcoholic fatty liver disease in Asian Indians residing in north India

OBJECTIVE

We analysed the associations of 25 hydroxy vitamin D [25(OH) D] and parathyroid hormone (PTH) levels with clinical, anthropometric, biochemical and body composition parameters in Asian Indians with nonalcoholic fatty liver disease (NAFLD).

METHODS

In this case-control study, 162 cases and 173 age and sex matched controls were recruited. Clinical, anthropometric, biochemical parameters and liver ultrasound were done. Percentage body fat (%BF), lean body mass and bone mineral density (BMD) were assessed by dual energy X-ray absorptiometry (DXA). Fasting insulin levels, value of homeostasis model assessment of insulin resistance (HOMA-IR), serum 25(OH) D, calcium and PTH levels were measured.

RESULTS

Subjects with NAFLD had lower serum 25(OH) D (19.4 ± 8.5 vs. 27.8 ± 9.4 ng/ml, p = 0.0001) and higher serum PTH (54.9 ± 19.5 vs.41.5 ± 18.3 pg/ml, p = 0.0001) levels as compared to controls. We observed significantly high values of systolic blood pressure (p = 0.002), waist circumference (p = 0.05), serum triglycerides (p = 0.002), total cholesterol (p = 0.002), alanine transaminase (p = 0.05), fasting insulin (p = 0.02) and HOMA-IR (p = 0.03) in the lowest 25(OH) D quartile. Multivariable-logistic regression showed that low serum 25(OH) D [OR (95%CI): 4.46 (2.58-7.72), p = 0.0001] and high PTH [OR (95%CI): 2.21 (1.50-3.30), p = 0.0001] level were independently associated with NAFLD.

CONCLUSION

Low serum 25(OH) D and high PTH levels were independently associated with the presence of NAFLD in Asian Indians residing in north India.

Study protocol: the effect of vitamin D supplements on cardiometabolic risk factors among urban premenopausal women in a tropical country -- a randomized controlled trial

BACKGROUND

Besides its classical role in musculoskeletal diseases, vitamin D deficiency has recently been found to be associated with cardiometabolic risks such as hypertension, diabetes mellitus and hypercholesterolemia. Although Malaysia is a sunshine-abundant country, recent studies found that vitamin D deficiency prevalence was significantly high. However, few published studies that measured its effect on cardiometabolic risk factors were found in Malaysia. There are also limited clinical trials carried out globally that tried to establish the causality of vitamin D and cardiometabolic risks. Therefore, a double blind, parallel, randomized controlled trial on vitamin D and cardiometabolic risks is planned to be carried out.The objective of this study is to investigate whether vitamin D supplements can reduce the cardiometabolic risk and improve the quality of life in urban premenopausal women with vitamin D deficiency.

METHODS/DESIGN

Three hundred and twenty premenopausal women working in a public university in Kuala Lumpur, Malaysia will be randomized to receive either vitamin D supplement (50,000 IU weekly for 8 weeks and 50,000 IU monthly for 10 months) or placebo for 12 months. At baseline, all participants are vitamin D deficient (≤ 20 ng/ml or 50 nmol/l). Both participants and researchers will be blinded. The serum vitamin D levels of all participants collected at various time points will only be analysed at the end of the trial. Outcome measures such as 25(OH) D3, HOMA-IR, blood pressure, full lipid profiles will be taken at baseline, 6 months and 12 months. Health related quality of life will be measured at baseline and 12 months. The placebo group will be given delayed treatment for six months after the trial.

DISCUSSION

This trial will be the first study investigating the effect of vitamin D supplements on both the cardiometabolic risk and quality of life among urban premenopausal women in Malaysia. Our findings will contribute to the growing body of knowledge in the role of vitamin D supplements in the primary prevention for cardiometabolic disease.

TRIAL REGISTRATION

ACTRN12612000452897.

Vitamin D3 and insulin combined treatment promotes titanium implant osseointegration in diabetes mellitus rats

This study investigated the effect of insulin and vitamin D(3) (VD(3)) treatment on implant osseointegration in diabetic mellitus (DM) rats. DM was induced by administration of streptozotocin in rats, which received implants insertion in the femur. Then animals were subjected to different treatment and divided to the following group: control, diabetic, insulin-treated diabetic, VD(3)-treated diabetic, insulin and VD(3) combination-treated diabetic rats. The glucose levels and weight of rats were periodically evaluated, and serum 25(OH)D(3) levels in rats were measured at the end of the experiment. Animals were sacrificed at 12 weeks after surgery, the peri-implant trabecular microstructure, implant fixation and implant osseointegration were measured by microscopic computerized tomography (micro-CT) evaluation, push-out test and histomorphometric analysis. Diabetic rats displayed significantly higher blood glucose level, lower body weight, lower serum 25(OH)D(3) levels, and less implant osseointegration than controls. Insulin treatment showed restorative effect on body weight and serum 25(OH)D(3) levels of diabetic rats, but the blood glucose level in diabetic rats were still substantially higher compared to controls after 14 days therapy of insulin. Combined treatment restored hyperglycemia in diabetic rats to be normal, and reversed the impaired osseointegration capacity of implants, with the bone volume ratio and percent osseointegration increased by 1.37-fold and 1.6-fold in micro-CT evaluation, the maximal push-out force and ultimate shear strength by 1.3-fold and 2.1-fold in push-out test, and the bone-to-implant contact and bone area ratio increased by 2.57-fold and 1.44-fold in histomorphometric analysis. Monotreatment also enhanced implant fixation, but less. These results indicated that insulin and VD(3) combined treatment may be an effective approach to enhance implant fixation in diabetic rats, but whether the results could be extrapolated to human needs further study.

Therapeutic implications of vitamin D and calcium in overweight women with polycystic ovary syndrome

OBJECTIVE

To assess effects of vitamin D and Calcium (Ca) on hormonal and metabolic milieu of polycystic ovary syndrome (PCOS).

DESIGN

Single arm open label trial.

METHODS

Twelve overweight and vitamin D deficient women with PCOS underwent a 2 hour oral glucose tolerance testing at baseline and following 3-month supplementation with vitamin D (daily dose of 3533 IU, increased to 8533 IU after the first five participants) and 530 mg elemental Ca daily.

MAIN OUTCOME MEASURES

Blood pressure (BP), plasma glucose, insulin, total testosterone (T) androstenedione (A), sex hormone binding globulin, lifestyle parameters were assessed at baseline and following 3-month intervention. Insulin resistance (IR) and area under the curve for glucose and insulin were computed; paired analyses were conducted.

RESULTS

Improved serum 25OHD (p < 0.001) and reductions in total T (p = 0.036) and A (p = 0.090) levels were noted following 3-month supplementation, compared to baseline. Significant lowering in BP parameters was seen in participants with baseline BP ≥ 120/80 mmHg (n = 8) and in those with baseline serum 25OHD ≤20 ng/ml (n = 9). Parameters of glucose homeostasis and IR remained unchanged (p > 0.05).

CONCLUSIONS

Androgen and BP profiles improved followed three month intervention, suggesting therapeutic implications of vitamin D and Ca in overweight and vitamin D deficient women with PCOS.

1,25(OH)2D3 inhibits the deleterious effects induced by high glucose on osteoblasts through undercarboxylated osteocalcin and insulin signaling

Diabetes mellitus (DM) is associated with multiple skeletal disorders, and vitamin D may play a functional role in the preservation of glucose tolerance. However, the relationship between vitamin D deficiency and DM is not well known. The aim of this study was to investigate the potential molecular link between 1,25(OH)(2)D(3) regulation and glucose homeostasis. Rat primary osteoblasts were cultured in different conditioned medium: normal glucose, high glucose, high glucose and insulin, high glucose and 1,25(OH)(2)D(3), high glucose and insulin and 1,25(OH)(2)D(3). The activity of osteoblasts was measured by cell viability, alkaline phosphatase and osteocalcin assay. The potential mechanism of how 1,25(OH)(2)D(3) affect insulin sensitivity was investigated by the assay of insulin receptor (IR) and vitamin D receptor (VDR) expression, and undercarboxylated osteocalcin (ucOC) level. The combined treatment has the strongest effect of inhibiting the deleterious effects induced by high glucose on osteoblasts, and it promoted the %ucOC value to approximately 40%, which is much higher than that in high glucose without treatment. Levels of IR and VDR of osteoblasts in combined treatment culture increased significantly compared with that in high glucose without treatment. So maybe 1,25(OH)(2)D(3) promotes insulin sensitivity of osteoblasts by activating insulin signaling and simultaneously stimulating ucOC secretion, which in turn regulate insulin production and sensitivity. 1,25(OH)(2)D(3) might be beneficial not only for diabetes, but also, for osteoporosis by promoting bone formation.

High prevalence of vitamin D insufficiency and its association with obesity and metabolic syndrome among Malay adults in Kuala Lumpur, Malaysia

BACKGROUND

Vitamin D status, as indicated by 25-hydroxyvitamin D is inversely associated with adiposity, glucose homeostasis, lipid profiles, and blood pressure along with its classic role in calcium homeostasis and bone metabolism. It is also shown to be inversely associated with metabolic syndrome and cardiovascular diseases in western populations. However, evidence from the Asian population is limited. Therefore, we aim to study the prevalence of vitamin D insufficiency (< 50 nmol/L) and the association of 25-hydroxyvitamin D with metabolic risk factors among an existing Malay cohort in Kuala Lumpur.

METHODS

This is an analytical cross sectional study. A total of 380 subjects were sampled and their vitamins D status (25-hydroxyvitamin D), fasting blood glucose, full lipid profile were assessed using venous blood. Systolic and diastolic blood pressure, weight, height and waist circumference were measured following standard protocols. Socio-demographic data such as sex, age, smoking status etc were also collected. Data was analysed using t-test, chi-square test, General Linear Model and multiple logistic regression.

RESULTS

Females made up 58% of the sample. The mean age of respondents was 48.5 (SD 5.2) years. Females had significantly lower mean Vitamin D levels (36.2; 95% CI: 34.5, 38.0 nmol/L) compared to males (56.2; 95% CI: 53.2, 59.2 nmol/L). Approximately 41% and 87% of males and females respectively had insufficient (< 50 nmol/L) levels of 25-hydroxyvitamin D (p < 0.001). The prevalence of Metabolic Syndrome for the whole sample was 38.4 (95% CI: 33.5, 43.3)%. In the multivariate model (adjusted for age, sex, abdominal obesity, HDL-cholesterol, diastolic blood pressure), insufficient Vitamin D status was significantly associated with 1-year age increments (OR: 0.93; 95% CI: 0.88, 0.98), being female (OR: 8.68; 95% CI: 5.08, 14.83) and abdominal obesity (OR: 2.57; 95% CI: 1.51, 4.39). Respondents with insufficient vitamin D were found to have higher odds of having Metabolic Syndrome (OR: 1.73; 95% CI: 1.02, 2.92) after adjusting for age and sex.

CONCLUSIONS

Our results highlight the high prevalence of vitamin D insufficiency among Malay adults in Kuala Lumpur. Vitamin D insufficiency is independently associated with younger age, female sex and greater abdominal obesity. Vitamin D insufficiency is also associated with Metabolic Syndrome.

Vitamin D status and its associated factors of free living Malay adults in a tropical country, Malaysia

Vitamin D status is influenced by sun exposure, geographic latitude, daily outdoor activities, body surface exposed to sunlight and dietary intakes. Malaysia, is sunny all year round. However, the vitamin D status of this population especially among the healthy and free living adults is not known. Therefore a study of vitamin D status and associated factors was initiated among an existing Malay cohort in Kuala Lumpur. A total of 380 subjects were sampled to have their vitamin D status assessed using 25-hydroxyvitamin D (25(OH)D). A short questionnaire enquiring socio-demographic characteristics, exposure to sunlight and clothing style was administered. Their mean age was 48.5±5.2years and the mean 25(OH)D for males and females were 56.2±18.9nmol/L and 36.2±13.4nmol/L respectively. There were significant positive correlation for sun exposure score (r=0.27, p<0.001) and negative correlation for sun protection score (r=-0.41, p<0.001) with 25(OH)D levels. In the logistic regression model, females (OR=2.93; 95% CI: 1.17, 7.31), BMI (1.1; 1.03, 1.20) and sun exposure score (0.998; 0.996, 0.999) were significantly associated with vitamin D status as represented by 25(OH)D levels. Our findings show that obesity, lifestyle behaviours and clothing style are directly associated with our participants especially females' low vitamin D status.

Hypovitaminosis D and cardiometabolic risk factors among non-obese youth

Hypovitaminosis D and increased cardiometabolic risk have been well established in adults. This study aims to determine whether or not vitamin D also influences cardiometabolic risk in children and adolescents. To test this hypothesis, we recruited 186 boys (mean age 12.4 ± 3.7 years) and 114 girls (11.6 ± 3.7) in a cross-sectional observational study. Anthropometrics were obtained and morning fasting blood samples were collected. Serum glucose and lipid profile were determined using routine methods. Serum 25-hydroxyvitamin D was quantified using an enzyme-linked immunosorbent assay. In our population, approximately 10% of subjects had severe 25-hydroxyvitamin D deficiency (< 12.5 nmol/L), while 50% of the boys and 40% of the girls had mild vitamin D deficiency (12.5–24.9 nmol/L). Circulating 25-hydroxyvitamin D concentrations were inversely correlated with age, body mass index (BMI), blood pressure, waist and hip circumferences and serum triglyceride concentrations, and positively associated with HDL-cholesterol. Age and systolic blood pressure were significant predictors of 25-hydroxyvitamin D, explaining about 30% of the variance (p = 0.0005). In conclusion, significant associations between serum 25-hydroxyvitamin D and cardiometabolic parameters support promising cardioprotective benefits from vitamin D sufficiency at an early age. Follow-up with prospective clinical intervention studies are needed to validate this hypothesis.

Vitamin D status and metabolic syndrome in Asian Indians

In this study, we aimed to estimate serum 25-hydroxy vitamin D (25-OH-D) in Asian Indians and test for association between 25-OH-D levels, insulin resistance (IR) and metabolic syndrome (MS). Serum 25-OH-D was measured in a cross-sectional sample of 441 Indians, aged 39.7 ± 12.8 years (237 men and 204 women) with 27.9% prevalence of MS. Vitamin D insufficiency (12.5 to <50 nmol l(-1)) and hypovitaminosis D (50 to <100 nmol l(-1)) were present in 65.6 and 31.1% of participants, respectively. The 25-OH-D levels did not differ significantly between sexes (P=0.057). Multivariate regression analysis indicated a positive relationship between 25-OH-D and β-cell function (homeostasis model assessment (HOMA)-B; β=0.245, P=0.006), whereas regression coefficients for fasting glucose (β=0.262, P=0.794), insulin (β=-0.140, P=0.889) and HOMA-IR (β=-0.119, P=0.172) were insignificant. Sex-stratified analysis showed no linear trend for increasing quintiles of 25-OH-D with prevalence of MS or its components (P>0.05). Although highly prevalent, vitamin D insufficient status was not associated with MS or IR in Asian Indians of either sex.