Atherosclerotic heart disease is one of the most common complications in Diabetes Mellitus. Paraoxonase (PON1) is an enzyme bound to high density lipoproteins (HDL) that has antioxidant activity; therefore it is considered to possess antiatherogenic properties. The present study shows the results obtained with a sample of 90 Diabetes Mellitus type 2 patients who attended Clínica Especializada de Diabetes Mellitus at Hospital Santo Tomás for control. The arylesterase activity of paraoxonase was higher in the diabetic group than in the control group. However, the difference was statistically not significant (p>0.05). Apparently, the age has no influence on the arylesterase activity of PON1 in the diabetic group. As expected, most of these patients presented abnormal lipid concentration (dyslipidemia). The correlation found between HDL-cholesterol (C-HDL) and the arylesterase activity of PON1 is weak. We also found a weak negative correlation between the serum glucose and the arylesterase activity of PON1, not only in the diabetic group, but also in the control group. From these results altogether, we can not conclude that the activity of PON1 is altered in individuals suffering from Diabetes Mellitus type 2. However, a possible explanation of these results is discussed.