Tryptophan and serotonin levels as potent biomarkers in diabetes mellitus complications: a new approach of diagnostic role

Alterations in the serotonergic system were verified to act a role in the pathogenesis of altered neurological and psychiatric diseases. In recent years, Tryptophan (Trp) and serotonin (5-HT) levels have been considered potent biomarkers of diabetes mellitus (DM). The different Trp metabolism may also play roles in the pathogenesis of DM and mounting risk of complications. The whole blood (WB) 5-HT level was mainly lower among diabetic patients compared to others. That is mostly derived from a lower platelet concentration of 5-HT in these patients. Indeed, 5-HT level can be considered a potent biomarker for early detection of DM complications. Besides, it was proved that outside the digestive and central nervous systems, 5-HT was discovered in beta cells, and scientists have been attempting to realize its mechanism of action ever since. Towards to end, the determination methods, biomarker’s role, and approaches of 5-HT and Trp levels were thoroughly investigated in both healthy and diabetic patients with or without complications. Moreover, the association between insulin and 5-HT has been specifically discussed. Our study concluded that Trp and 5-HT levels could be exclusively applied for early diagnosis of DM complications as well as many other complications.