The aim of this study was to evaluate the activity of semicarbazide-sensitive amine oxidase (SSAO) and the total nitrite and nitrate (NO _x ) concentrations in serum from type 2 diabetic patients and control subjects in order to evaluate if they could be used as novel diabetic markers. We studied 38 type 2 diabetic patients and 35 control subjects. Serum samples from those subjects were evaluated by radiochemical methods for SSAO activity using ¹⁴C-benzylamine. Serum NO _x concentrations were obtained as an index of nitric oxide production by the Griess reaction. Serum SSAO activity was higher in type 2 diabetic patients than in control group and serum SSAO in type 2 diabetic correlated with age, serum creatinine and total cholesterol. Serum NO _x levels in type 2 diabetic patients were also significantly higher than those in the control group. Serum NO _x levels in control group correlated with serum SSAO activity. In conclusion, the increase in the SSAO activity and NO _x levels observed in type 2 diabetic patients could be parameters to take in account and play relevant role in diabetes development. SSAO and NO _x are suggested as markers for prognostic of diabetes.