Abstract: The level of 5-hydroxytryptamine (5-HT) in group of diabetes with hypertension was significantly lower than in type 2 diabetes group and normal control. The level of platelet 5-HT was negatively related with systolic pressure, diastolic pressure and serum triglyceride. Hypertension and dyslipidemia in coordination with each other enhanced the platelet 5-HT release in diabetes.