Esterases were studied in serum samples from 141 patients with hyperlipidaemia and 27 patients with hyperlipidaemia and non-in- sulin-dependent diabetes mellitus. The control group consisted of 322 non-diseased individuals. Paraoxon, beta-naphthylacetate and phenylacetate were used as substrates. Enzyme activities were measured in the absence and presence of EDTA in order to differentiate the EDTA-sensitive (y-sen) from the EDTA-insensitive Ivins) enzymes. Activity ranges for a given enzyme and substrate grossly overlapped between all the studied groups. However, sera from the control group had significantly higher median v-sen and y-ins activities for paraoxon, and higher y-sen and y-ins activities for PA, than the two groups of patients. HDL-cholesterol, total cholesterol, triglycerides and lipidograms were determined in serum samples from the two groups of patients. Serum samples with type V lipidogram had the lowest y-sen and y-ins activities for paraoxon, the lowest HDL-cholesterol and the highest triglyceride concentrations
