Mean and Biological Variation of Insulin Resistance Is as High in Polycystic Ovarian Syndrome as Type 2 Diabetes.

A single assessment of insulin resistance OR) by using HOMA-IR is insufficient due to the known variability of this measure (and presumably that of IR) within the same individual. We compared the mean and biological variation in insulin resistance levels in patients with polycystic ovarian syndrome to that of type 2 diabetes (T2DM) by repeated measurements of HOMA-IR thereby arriving at a value which represents the mean of the variation. The biological variation of IR was assessed by measuring IR at four day intervals on 10 consecutive occasions in 12 overweight patients with PCOS (BMI means ± SD; 33.2 ± 6.3), 12 postmenopausal Caucasian subjects with diet controlled T2DM (31.1 ± 3.3), 11 healthy women with normal menstrual periods (29.9 ± 3.25) and 11 healthy postmenopausal women (32.4 ± 5.3). The diagnosis of PCOS was based on the Rotterdam criteria. Plasma glucose was analyzed in singleton and serum samples were split before assay. Group differences were compared by analysis of variance. Where significant differences were indicated Scheffe's post-hoe test was applied. No significant difference in BMI was observed between all the groups, p=0.37. The HOMA-IR was 5.9±5.3 (mean±SD) in women with PCOS, 4.3±2.3 in postmenopausal T2DM, 1.7±0.6 in pre-menopausal women and 2.1±0.8 in postmenopausal women. All pairwise comparisons for HOMA-IR were significantly different (p = 0.005) except PCOS vs postmenopausal T2DM, postmenopausal T2DM vs healthy postmenopausal and healthy premenopausal vs healthy postmenopausal. Mean intraindividual variation of PCOS, postmenopausal T2DM, healthy pre-menopausal and healthy post-menopausal were 1.19, 1.05, 0.3, 0.15 respectively. This is the first analysis to show that when repeated measurements of HOMA-IR are made, the mean and biological variation of insulin resistance in PCOS women is as high as those seen in postmenopausal women with diet controlled T2DM, which in turn, is relatively greater than their age matched peers. Since insulin resistance itself is an independent predictor of vascular risk, it would support the hypothesis that there is increased cardiovascular risk in women with PCOS. [ABSTRACT FROM AUTHOR]