Aldehyde dehydrogenase activity and vascular disease in type II diabetes--a comparison between 2 different assays for activity.

We have recently reported that type II diabetic subjects with macroangiopathy have a higher activity of aldehyde dehydrogenase (ALDH) in blood than those without clinical vascular disease. ALDH activity was measured as the elimination of acetaldehyde added to a blood homogenate in vitro. We have re-examined our clinical material with another assay of ALDH which uses indole-3-acetaldehyde as substrate and measures the formation of indole-3-acetic acid. A negative correlation between the half-life of acetaldehyde and the formation of indole-3-acetic acid was found in the group of subjects free from vascular disease (r = -0.55, p less than 0.01). Thus, a rapid elimination of acetaldehyde corresponded to a rapid formation of indole-3-acetic acid. No such correlation was found in subjects with macroangiopathy. These results suggest that the 2 groups, with and without clinical vascular disease, have differences in isoenzyme composition, in the kinetic properties of the enzyme, or in the non-enzymatic binding of acetaldehyde.