Objective, design and methods: Circulating levels of interleukin-6 (IL-6) and C-reactive protein (CRP) were determined in 59 women with polycystic ovary syndrome, of whom 37 were retested after receiving metformin for 6 weeks and 6 months, to ascertain the response of these inflammatory markers to weight loss and insulin sensitization.
Results: IL-6 levels correlated significantly with body mass index (BMI; r = 0.55), homoeostasis model insulin resistance index (HOMA-R; r = 0.47) and CRP (r = 0.59). On multiple regression analysis, adiposity rather than IL-6 accounted for most of the variability of CRP independently of insulin resistance, while IL-6 remained closely with adiposity. After 6 weeks of metformin therapy (n = 37) there was a significant reduction in BMI (p < 0.001), waist (p < 0.001) and CRP (p < 0.01), while at 6 months there was not only a significant reduction in BMI and waist but also in HOMA-R (p = 0.01) and IL-6 levels (p < 0.01) with no further reduction of CRP.
Conclusions: In polycystic ovary syndrome, obesity rather than IL-6 or insulin resistance is the main determinant of CRP. While short-term metformin therapy facilitates weight loss with a concomitant reduction in CRP, long-term therapy results in a reduction of IL-6 and insulin resistance. Metformin-associated reduction of CRP levels prior to any significant changes in insulin resistance or IL-6 perhaps involves different mechanisms of action.
Copyright 2009 S. Karger AG, Basel.