Non-systematic literature review that focuses on the roles of serotoninergic system in diabetes mellitus pathophysiology and its related pharmacological targets. It is described the biochemistry and physiology of 5-hidroxitriptamine (5HT), as well as its carrier, 5HT receptors families and subtypes in regulatory actions of carbohydrates metabolism, insulin and glucagon secretion, and appetite control in coactivation with leptin. Were included studies related to serotonin role in carcinoid syndrome and diabetes vascular complications, and studies about measurement of metabolites (5-hidroxindolacetic acid and xanturenic acid) as potential biomarkers of diabetes. Finally, it is introduced the evidence of the hipoglicemiant effect of three groups of serotonin metabolism regulatory medicines: selective serotonin reuptake inhibitors, 5HT-receptors agonists and antagonists, and 5-tryptophan-hidroxilase (Tph) enzymes antagonists.