In view of the elevated levels of circulating 5-HT due to the enhancement of platelet aggregation in diabetes [20,21,22,23], sarpogrelate, a 5-HT2A receptor antagonist, has been shown to exert beneficial effects in attenuating a wide variety of abnormalities in chronic diabetes [24,25,26,27,28,29,30,31]. This evidence concerns the gene HTR5A and diabetes mellitus.