Associations between Vitamin D Levels and Insulin Resistance in Non-Diabetic Obesity: Results from NHANES 2001-2018

Abstract

Objective

Obesity is often accompanied by insulin resistance (IR) and diabetes. We explored the association between vitamin D levels and IR in non-diabetic obesity.

Methods

We conducted a cross-sectional study based on the data of National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018. Non-diabetic individuals (aged ≥20 years) with obesity (BMI ≥ 30kg/m²) were included in the study. And HOMA-IR ≥ 2.5 was defined as IR. The multivariable linear regression models were constructed to evaluate the associations between levels of 25(OH)D and HOMA-IR. We calculated the odds ratio (OR) and 95% confidential intervals (CIs) for associations between 25(OH)D deficiency and IR in obesity using multivariable logistic regression models.

Results

Overall, a total of 3887 individuals were included in this study. Serum vitamin D level was significant lower in obesity participants with IR than that of non-IRs. The linear regression models showed that vitamin D level was inversely associated with HOMA-IR in obesity after adjusting for covariables (β=-0.15, 95%CI (-0.28, −0.02), p = 0.028). And the multivariable logistic regression models indicated an association between vitamin D deficiency and IR in obesity ((OR= 1.38, 95%CI (1.09-1.73), p = 0.007)). The further stratified regression analyses among different BMI demonstrated that vitamin D deficiency (OR = 1.4, 95%CI (1.05,1.86), p = 0.022) only contributed to developing IR in class I obesity.

Conclusion

This study suggested an association of vitamin D levels with IR in obesity. And vitamin D deficiency contributed to IR in class I obesity.

Keywords:

• Insulin resistance
• vitamin D
• obesity
• NHANES

Acknowledgments

We thank all of people who contributed to the National Health and Nutrition Examination Survey data, including all of the anonymous participants in the study.

Disclosure statement

The authors have declared that no conflict of interest exists. The authors have nothing to disclose.

Data availability statement

The datasets are available at NHANES website (http://www.cdc.gov/nchs/nhanes.htm).

Additional information

Funding

This work was supported by Nanjing Medical Science and Technology Development Fund (ZKX22038).