Abstract
The metabolic syndrome is a group of cardio metabolic risk factors characterized by adipose tissue malfunction and insulin resistance. Insulin resistance might be one of the main reasons of many metabolic disturbances as well as dysregulation of the blood glucose level. In recent years, the relationship between vitamin D and insulin resistance has been a topic of debate and growing broad interest. In fact, vitamin D serum level may be one of the factors accelerating the development of insulin resistance. Vitamin D deficiency is a common abnormal condition in the population and may be involved with the pathogenesis of diseases related to insulin resistance, such as obesity, diabetes, hyperlipidemia and polycystic ovary syndrome (PCOS). In addition, there are several researches that recommended the use of vitamin D to improve insulin resistance in patients with metabolic disorders, but the mechanism by which the vitamin works to produce this effect is still a matter of debate among researchers. the aim of this review is to summarize the recent evidence suggest mechanisms by which vitamin D can improves insulin sensitivity.