Usefulness of Insulin Sensitivity Indexes derived from Oral Glucose Tolerance Test in Women with Polycystic Ovary Syndrome

Abstract

- Abstract Background: Insulin resistance is prevalent in women with polycystic ovary syndrome (PCOS), and it makes them to have high risk for development of type 2 diabetes. Evaluation of insulin sensitivity would be important to predict their risks. Although the euglycemic-hyperinsulinemic clamp technique is the gold standard for measuring insulin sensitivity, it is too hard to practice in large epidemiologic studies. The aim of this study is to verify the validity of various insulin sensitivity indexes f rom oral glucose tolerance test (OGTT) in women with PCOS. Methods: We performed euglycemic-hyperinsulinemic clamp (target glucose; 90 mg/dL, insulin ;~1 mU/kg․min) to obtain insulin-mediated glucose disposal rate (M-value) in 62 non-diabetic women with PCOS (BMI < 23 kg/m 2 ; n = 37, BMI ≥ 23 kg/m 2 ; n = 25). Homeostasis model assessment [HOMA(IR)], quantitative insulin sensitivity check index (QUICKI), glucose to insulin ratio (G/I ratio), whole body insu lin sensitivity index [ISI (COMP)], metabolic clearance rate of glucose [MCRest-OGTT 1,2 ], and insulin sensitivity indexes [ISIest-OGTT 1,2 ] were calculated from plasma glucose and insulin levels from standard 75-g OGTT. The correlations of various insulin sensitivity indexes f rom OGTT with M-value were evaluated. Results: In lean women with PCOS (BMI < 23 kg/m 2 , n = 37), ISI(COMP) (r = 0.36, P < 0.05), MCRest-OGTT 1 (r = 0.49, P < 0.01), ISIest-OGTT 1 (r = 0.50, P < 0.01), MCRest-OGTT 2 (r = 0.45, P < 0.01) and ISIest-OGTT 2 (r = 0.40, P < 0.05) were significantly correlated with M-value. In overweight and obese women with PCOS (BMI ≥ 23 kg/m 2 , n = 25), HOMA(IR) (r = -0.40, P < 0.05), QUICKI (r = 0.40, P < 0.05), MCRest-OGTT 1 (r = 0.76, P < 0.001), ISI est-OGTT 1 (r = 0.63, P < 0.001), MCRest-OGTT 2