Conclusion
We have presented the first 450K DNA methylation array assessment of women with PCOS compared at initial diagnosis to women with PCOS who later developed diabetes. Despite the limitations of a small sample study, we have identified multiple loci of differential DNA methylation between these clinical phenotypes. We suggest that DNA methylation holds exciting potential for identifying clinically-usable prognostic biomarkers that may help identify women likely to develop diabetes at an early stage where lifestyle interventions may be effective in reducing risks of diabetes and other complications of PCOS.