The Association Among Vitamin D, Insulin Resistance, and Obesity in Turkish Women

Abstract

Background: Vitamin D deficiency is common in patients with body mass index (BMI) higher than 25 kg/m2. The aim of this study was to evaluate whether any correlation exists among 25 hydroxyvitamin D, BMI, and other biochemical parameters in Turkish women subjects. Methods: A total number of 31 subjects with BMI ≥ 25 kg/m2 were included. These patients were, subsequently, divided into 2 groups according to their BMI. Group 1 consisted of patients with BMI:25 - 34 kg/m2 and group 2 with BMI ≥ 35 kg/m2. Venous blood samples were collected from the subjects in a morning fasting state to measure serum Vit D levels. high performance liquid chromatography-mass spectrometry (HPLC-MS) method was used for Vit D measurement. The homeostatic model assessment (HOMA) was used to quantify insulin resistance (IR). Results: A total number of 15 subjects (46.9%) had BMI 25 - 34 kg/m2 (group 1) and 17 subjects had BMI ≥ 35 kg/m2 (group 2). Vit D levels were 24.82 ± 13.7 ng/mL in group 1 and 23.56 ± 12.31 ng/mL in group 2. Although Vit D levels were lower than normal limits in both groups, they were not statistically different among the groups (p 0.901). Although statistically insignificant, insulin levels were higher in group 2 than group 1 (19.68 ± 7.91 µU/mL vs 17.6 ± 12.02 µU/mL; P = 0.29) and insulin levels were negatively correlated with Vit D (r = -0,631; P = 0,002; P < 0,05). HOMA-IR levels were insignificantly higher in group 2 patients than group 1 patients (5.10 ± 2.89 vs 4.19 ± 3.35; P = 0.25). HOMA-IR was negatively correlated with Vit D (r = -0,456; P = 0.05). Conclusions: We demonstrated decreased Vit D levels and a negative correlation among serum insulin levels, HOMA-IR, and Vit D in Turkish obese women. Epidemiological studies, also, indicate that Vit D deficiency may be related with IR and the development of diabetes. Further studies are needed.