It has been shown that the level of APN, is decreased in metabolic syndromes such as, obesity, cardiovascular disease and T2DM.87 At the level of animal experimental models, APN is protective against these diseases in addition to other T2DM-related diseases, including atherosclerosis, osteoporosis, and chronic pulmonary obstructive disease.57,87 In the nervous system, APN may be neuroprotective against ischemia, depression and other brain conditions.57,87. Here, ANPEP is linked to depressive disorder.