In addition to the anti-obesity activity of M-LB/CS, the present results imply that the administration of the three different doses of M-LB/CS not only preserve exocrine function, but also enhance insulin sensitivity by inhibiting the abnormal expansion of pancreatic islets and by decreasing blood levels of glycosylated hemoglobin, insulin, and glucose in mice fed the HFD. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.