METRNL and Insulin resistance: Up to date, the spectrum of Metrnl functions and mechanism need to be investigated.10 Previous study has showed that adipocyte Metrnl controls insulin sensitivity by the peroxisome proliferator-activated receptor gamma (PPAR) pathway, acts as an insulin sensitizer and possibly a therapeutic target for insulin resistance.11-13 Another report argued that up-regulation in peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1), as an important regulator that induces mitochondrial biogenesis and increases Metrnl in muscle tissue.