To evaluate the inheritance of cardiovascular risk parameters in subjects with increased susceptibility for non-insulin-dependent diabetes mellitus, we compared 25 pairs of healthy twins who were offspring of diabetic parents with 25 pairs without a parental history for type 2 diabetes mellitus (12 monozygotic and 13 dizygotic in each group). Environmental factors were also evaluated to avoid bias in the assessment of concordance. No significant difference was found in concordance between monozygotic and dizygotic twins for physical activity, diet, smoking, alcohol intake and living together or apart. Genetic analysis revealed a substantial heritability for weight, body mass index, percentage of body fat, lipoprotein(a), high density lipoprotein (HDL)- and HDL2-cholesterol, without significant differences between the two groups. We conclude that heritability of several cardiovascular risk parameters is not increased in subjects with increased susceptibility to type 2 diabetes mellitus.