Circulatory changes of the novel adipokine adipolin/CTRP12 in response to metformin treatment and an oral glucose challenge in humans

Abstract

Adipolin/CTRP12 is a novel adipokine with anti-inflammatory and glucose-lowering properties in rodents. We sought to investigate the effects of metformin treatment (850mg twice daily for 6months) and a 2h 75g oral glucose tolerance test (OGTT) on serum adipolin concentrations in humans. Cross-sectional study [PCOS (n=83) and control (n=39) subjects]. Serum adipolin was measured by ELISA. Metformin treatment (850mg twice daily for 6months) was offered to all women with PCOS, 34 women participated but 21 women completed 6months of metformin therapy. Reasons for subjects not completing the study were nausea and gastrointestinal side effects (n=4), pregnancies (n=5), noncompliance (n=2) and loss of contact (n=2). Metformin treatment (850mg twice daily for 6months) substantially increased serum adipolin concentrations (P<0·05) in women with polycystic ovary syndrome (PCOS), a pro-inflammatory state associated with obesity, diabetes, dyslipidaemia and atherosclerosis. Furthermore, changes in waist-hip ratio, glucose, triglycerides, CRP and carotid intima media thickness showed significant negative associations with changes in adipolin levels (P<0·05, P<0·01); in multiple regression analyses, only changes in glucose were predictive of changes in adipolin levels (β=-0·570, P=0·009). Serum adipolin decreased significantly in response to the OGTT in PCOS and control subjects at 90min (P<0·05) and 120min (P<0·01). Adipolin and/or novel pharmacologic agents that increase adipolin's circulating concentrations might constitute a novel approach in the treatment of insulin resistant states.