Role of vitamin D treatment in glucose metabolism in polycystic ovary syndrome.OBJECTIVE: To determine the effect of treatment with vitamin D(3) analogue in the parameters of glucose metabolism in obese women with polycystic ovary syndrome (PCOS). DESIGN: Observational study. SETTING: Obese women with PCOS in an academic research environment. PATIENT(S): Fifteen obese women (mean age 28 +/- 1.3 years, mean body mass index 32.55 +/- 0.43) with documented chronic anovulation and hyperandrogenism were recruited into the study. INTERVENTION(S): Alphacalcidol (1-alpha-hydroxyvitamin D(3)) was administered orally 1 mug/day for 3 months. All subjects underwent a frequently sampled IV glucose tolerance test after a 10- to 12-hour overnight fast during a spontaneous bleeding episode before and after treatment with alphacalcidol. MAIN OUTCOME MEASURE(S): Peripheral insulin resistance and insulin effectiveness were estimated with minimal model. RESULT(S): The first phase of insulin secretion was significantly increased after treatment with alphacalcidol. A favorable statistically significant change also was observed in the lipid profile. CONCLUSION(S): Treatment with the vitamin D(3) analogue (alphacalcidol) could be of value in the management of PCOS.

I think the only way we will see progress with vit d is via analogues like this where people can profit from the intervention with a patented drug form.
Low serum 25-hydroxyvitamin D concentrations are associated with insulin resistance and obesity in women with polycystic ovary syndrome.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.

the obvious answer is to raise 25(OH)D to optimal 125nmol/l~175nmol/L using 100iu/daily/D3 for each 1ng or 2.5nmol/l required. But that's not going to make anyone any money you can buy effective strength D3 for peanuts. (it's even available and cheap in the UK now) So we'd better think of a reason why that may be dangerous and make people afraid of the natural product that is biologically identical to the stuff our skin makes or they won't want to pay lots of money for our patented synthetic version will they?