Human blood samples.
Peripheral blood samples were obtained from women with PCOS diagnosed >12 months prior to sample collection using Rotterdam diagnostic criteria[1] (West Midlands (Black Country) Research Ethics Committee 15/WM/0162). Repository samples with long-term clinical data enabled identification and comparison of six ‘control’ (women with PCOS), and six ‘case’ women with PCOS who developed diabetes (median three years) following sample collection (demographics in TableS1 ). Samples were matched by ethnicity, and where possible by age, BMI, smoking status, and co-morbidity. No patient had prior history of endocrine/metabolic disorder, malignancy or systemic chemotherapy.