title: The mean and the biological variation of insulin resistance does not differ between polycystic ovary syndrome and type 2 diabetes.
abstract: BACKGROUND
  There is an assumption that the mean and biological variation of insulin resistance (IR) is less in polycystic ovary syndrome (PCOS), and intuitively higher in type 2 diabetes (T2DM). To test this hypothesis we compared the mean and biological variation in IR in PCOS to that of T2DM and to age- and weight-matched controls.
  
  
  METHODS
  Twelve PCOS, 11 matched healthy women; 12 postmenopausal diet-controlled T2DM and 11 matched healthy postmenopausal women were recruited. Blood samples were collected at 4-d intervals on 10 consecutive occasions. The biological variability of IR was derived on duplicate samples.
  
  
  RESULTS
  Mean and biological variability of HOMA-IR for PCOS did not differ from T2DM. Both measures were higher than the matched controls. There was no difference in insulin or IR measures between the body mass index matched pre- and postmenopausal women. Percentage beta cell function were 208.8%, 62.3%, 106.5% and 111.9%, respectively, in PCOS, postmenopausal women with T2DM, healthy premenopausal and healthy postmenopausal women.
  
  
  CONCLUSIONS
  The progression from PCOS to the development of T2DM is unlikely to be due to a further increase in IR (or variability), but rather the progressive failure of pancreatic beta cells with a decrease in insulin production. The clinical trial registration number for this study is ISRCTN65353256.
authors.affiliation: Department of Medicine University of Hull, Hull Royal Infirmary, Hull, UK. l.cho@hull.ac.uk
authors.forename: Li Wei
authors.initials: LW
authors.lastname: Cho
authors.forename: V
authors.initials: V
authors.lastname: Jayagopal
authors.forename: E S
authors.initials: ES
authors.lastname: Kilpatrick
authors.forename: S L
authors.initials: SL
authors.lastname: Atkin
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D011085:Polycystic Ovary Syndrome / Q000473:pathology / Q000503:physiopathology*