For instance, adult zebrafish fed with a long‐term HFD developed T2DM and reported higher body weight and body mass index, more lipid vacuoles in the liver, increased insulin transcription levels in the liver, brain and muscle, and high fasting blood glucose, whereas insulin signalling pathway and glucose transport were impaired in the insulin‐targeting tissues (Table 2) (Meng et al., 2017). Here, INS is linked to type 2 diabetes mellitus.