Effect of 25-hydroxyvitamin D on metabolic parameters and insulin resistance in patients with polycystic ovarian syndrome

To investigate the correlation between the levels of 25-hydroxyvitamin D and insulin resistance in patients with polycystic ovarian syndrome (PCOS). In 30 untreated PCOS patients and 15 control subjects, levels of 25-hydroxyvitamin D were measured. In addition, endocrine and metabolic variables were evaluated and a glucose tolerance test was performed to assess indices of insulin resistance. Obese PCOS women (n = 15) had lower 25-hydroxyvitamin D levels than lean PCOS women (n = 15) and control subjects (8.9 ± 3.1 vs 26.5 ± 6.4 vs 79.2 ± 19.1 nmol/l respectively; P < 0.001). In the entire cohort, 25-hydroxyvitamin D levels were negatively correlated with body mass index (r = −0.390), fasting insulin (r = −0.707), HOMA-β (r = −0.705), and HOMA-IR (r = −0.635), and positively correlated with QUICKI (r = 0.723) (all P < 0.001). In PCOS women, low 25-hydroxyvitamin D levels are associated with obesity and insulin resistance.