AIMS

Prediabetes is a public health problem, and its prevalence is increasing worldwide. Both genetic factors and lifestyle contribute to the development and progression of prediabetes. The Omentin-1 Val109Asp polymorphism is reported to be associated with insulin resistance and obesity. Moreover, research suggests that vitamin D may help decrease the risk of developing and progressing to type 2 diabetes mellitus. Therefore, this trial aimed to investigate the interaction between vitamin D supplementation and the Omentin-1 gene polymorphism on metabolic factors, omentin-1 levels and obesity values in women with prediabetes.

MATERIALS AND METHODS

This double-blind randomized controlled trial was conducted on 204 women aged 18-65 with prediabetes. After obtaining informed consent, the blood samples of all participants were analysed to determine the Omentin-1 polymorphism (Val109Asp) genotypes. The women were then randomized into intervention (n = 24) and placebo (n = 24) groups (1:1) according to each genotype of the Omentin-1 polymorphism. In total, 96 women were allocated to receive vitamin D (50 000 IU) or a placebo every two weeks for 12 weeks. Anthropometric measures, dietary intake data and physical activity level information were collected at the beginning and after the intervention. Data analyses were performed using IBM SPSS Statistics software.

RESULTS

Vitamin D administration significantly increased serum levels of 25-hydroxyvitamin D (25(OH)D), insulin, HOMA-IR, HOMA-β and QUICKI in both AT and TT genotypes (all, p < 0.001). Moreover, the serum concentration of HDL-C decreased significantly after vitamin D intervention in the AT genotype, but not in the TT genotype (p < 0.001). A significant interaction was also observed between vitamin D intervention and Omentin-1 Val109Asp polymorphism on HDL-C (p = 0.003), waist circumference (WC) (p = 0.026) and waist-to-height ratio (WHthR) (p = 0.035). However, there was no significant interplay between vitamin D and Omentin-1 polymorphism on glycaemic factors, omentin-1 levels and other lipid profiles and anthropometric measures (p ≥ 0.05).

CONCLUSIONS

The findings suggest that the Omentin-1 gene Val109Asp polymorphism may modify the effects of vitamin D intervention on serum HDL-C levels and abdominal obesity in women with prediabetes. Future clinical trials are necessary to clarify the influence of the Omentin-1 gene polymorphism genotype on the effects of vitamin D intervention.