Low Serum 25-Hydroxyvitamin D Concentrations are Associated with Insulin Resistance and Obesity in Women with Polycystic Ovary Syndrome

Abstract

Insulin resistance (IR) and central obesity are common features of the polycystic ovary syndrome (PCOS). Vitamin D is thought to play a role in the pathogenesis of type 2 diabetes by affecting insulin metabolism. The aim of our study was to investigate the effect of 25-hydroxyvitamin D (25-OH-VD) on metabolic parameters and IR in PCOS. In 120 untreated PCOS patients (median age 28 years) levels of 25-OH-VD (radioimmunoassay method provided by DiaSorin), calcium and anorganic phosphate were measured. In addition, endocrine and metabolic variables were evaluated and a glucose tolerance test was performed to assess indices of IR. In the entire PCOS cohort, 25-OH-VD concentrations were negatively correlated with body mass index (r=-0.2765), body fat (r=-0.2490), HOMA-IR (r=-0.1947), hyperinsulinemia (r=-0.1892) and leptin levels (r=-0.2834), and positively correlated with HDL cholesterol (r=0.2630) (all p<0.05). Subgroup analysis of lean, overweight and obese women revealed significant higher 25-OH-VD levels in lean women. Differences remained significant when women were divided according to their 25-OH-VD levels. Women with hypovitaminosis D (<9 ng/ml) had higher mean BMI, indices of IR and leptin levels compared to women with normal serum levels (all p<0.05). Analysis of vitamin D and biochemical endocrine PCOS features revealed a significant correlation only between 25-OH-VD and sex hormone-binding globulin as well as the free androgen index. In conclusion, in PCOS women, low 25-OH-VD levels are associated with obesity and insulin resistance but not with PCOS per se.

Highly prevalence of vitamin D deficiency among Brazilian women of reproductive age

“…These results conflict with previous studies' findings that hypovitaminosis D is associated with PCOS (1). Furthermore, other authors have suggested that vitamin D deficiency is associated with PCOS only among obese women (30,31). Moreover, another study found that hypovitaminosis D was associated with insulin resistance, regardless of the patient's body mass index (32).…”

Low 25(OH)D3 levels are associated with total adiposity, metabolic syndrome, and hypertension in Caucasian children and adolescents

“…The biological mechanisms by which vitamin D may influence the MetS have not been completely elucidated. Several studies reported that 25(OH)D 3 was inversely related to percentage body fat (37,38), elevated BP (39-41), elevated glucose or IR (11,(42)(43)(44), and triglycerides (45) and positively associated with HDL-cholesterol (42). In particular, using data from the Third National Health Examination and Nutrition Survey (NHANES) (46).…”

The role of vitamin D in metabolic disturbances in polycystic ovary syndrome: a systematic review

“…Twelve studies had an observational design (18,19,20,21,22,23,24,25,26,27,28,29), employing a crosssectional or case-control design, with vitamin D status as one of the preliminary outcomes. A summary of these studies is given in Table 1.…”

“…The studies included premenopausal women (14-50 years) of various ethnicities, with the number of participants ranging from 45 to 400. Different stratifications were used: seven studies compared PCOS women with controls (19,20,22,23,24,27,28), three studies compared lean vs obese PCOS women (18,21,26), one study compared PCOS women with and without the metabolic syndrome (25), and one study solely included PCOS women (29). Large differences were found in the prevalence of vitamin D deficiency (defined as serum 25OHD levels !50 nmol/l), varying from 37% in a study carried out in Italy (21) to 72% in a study carried out in Scotland (19).…”