Sex-dependent association between circulating irisin levels and insulin resistance in healthy adults

• Inverse relationship between plasma irisin levels versus insulin levels and HOMA-IR in healthy subjects.
• Sex dependent effects of irisin on insulin, HOMA-IR and HDL-C.
• Plasma irisin levels were negatively associated with percent body fat (PBF) and body fat mass (BFM) in men but not women.
• Provided possible hormonal based hypothesis for gender based differences.

BackgroundIrisin, a myokine, expressed by muscle and adipose tissue, has been reported to stimulate conversion of white into brown adipose tissue. The beneficial health effects of exercise are thought to be mediated in part, via increased production of irisin.ObjectiveThe primary aim of this study was to assess the association between plasma irisin levels glycaemic indices in healthy adults. Associations between irisin and lipid levels, CRP and body composition were explored as secondary outcomes.MethodsA cross-sectional sample of forty nine (n = 49) free living healthy males (n = 28) and females (n = 21), between the ages of 18 and 65, with body mass index (BMI) within the healthy range, were recruited. Body weight, height, and body composition measurements were taken. Fasting blood samples were collected for the analysis of glucose, insulin and irisin levels. Insulin resistance score, HOMA-IR, was calculated using fasting blood glucose and insulin values. The relationship between plasma irisin levels and anthropometric measurements, glucose, insulin and HOMA-IR was determined using Spearman's bivariate correlation test.ResultsA significant inverse relationship was found between plasma irisin levels and insulin(r = −0.380; P = 0.007) and HOMA-IR(r = −0.362; P = 0.011). This relation was further strengthened in males when the data was stratified by gender. Circulating irisin levels were positively correlated with HDL-C (r = 0.39; P = 0.05) in male participants. Additionally, there was a significant negative correlation between percent body fat (r = −0.43, P < 0.05) and body fat mass (r = −0.47, P < 0.05) and circulating irisin levels in male participants.ConclusionsThis study reports a sex-dependent inverse relationship between plasma irisin levels and insulin resistance in healthy subjects.