Serum levels of the myokine irisin are predicted by markers of insulin resistance during pregnancy and after delivery
Objective: Irisin has recently been introduced as a novel myokine which reverses visceral obesity and improves glucose metabolism in mice. Therefore, we investigated circulating levels of this myokine in women with and without gestational diabetes mellitus (GDM) during pregnancy and after delivery.
Methods: For this study, 78 women with GDM and 78 healthy, pregnant, gestational age-matched controls were recruited. In a subset of these patients (46 GDM, 43 controls), postpartal follow-up data (median duration after delivery: 4.5 years) were available. Circulating levels of irisin were quantified using a commercial enzyme-linked immunosorbent assay. Furthermore, irisin serum levels were correlated to biochemical and anthropometric markers of glucose and lipid metabolism, renal function, and inflammation.
Results: Median [interquartile range] irisin levels did not differ between GDM (482.1 [147.8] µg/l) and control patients (469.5 [169.9] µg/l) during pregnancy (p = 0.377). In these patients, fasting insulin remained an independent predictor of serum irisin in multivariate analysis (β= 0.225, p = 0.019). After delivery, irisin was significantly higher in women after a GDM pregnancy (454.8 [145.8] µg/l) as compared to the control group (378.0 [114.7] µg/l) (p < 0.001). Again, markers of insulin resistance (fasting insulin, homeostasis model assessment of insulin resistance) positively and independently predicted irisin levels after delivery similar to the findings during pregnancy. Furthermore, C reactive protein was independently and positively associated with irisin after delivery.
Conclusions: Taken together, irisin is independently and positively associated with markers of insulin resistance during gestation and after delivery. Further investigations need to elucidate the pathophysiological significance of these findings.