Dicarboxylic acids as markers of fatty acid peroxidation in diabetes

Increased urinary excretion of dicarboxylic acids (DAs) has been well known in patients with diabetic ketoacidosis (DKA). It was known that small amou nts of such DAs were also detected in urine from healthy humans. Upon chemi cal, radiation-induced or enzymatic oxidation, cis-polyunsaturated fatty ac ids (PUFA) have previously been shown to generate saturated short- and medi um-chain length DAs. In diabetes, it was confirmed that the imbalance betwe en the generation of free radicals and antioxidant defense systems increase s oxidative stress and leads to the damage of lipid, which contains PUFA. S ome peroxidation products of PUFA, such as malondialdehyde and conjugated d iene, are generally known to be elevated in patients with diabetes. The pre sent study was undertaken to determine if urinary excretion of DAs is eleva ted in diabetic patients without DKA. Urine samples from ten non-ketoacidot ic patients with type 2 diabetes and ten healthy subjects were examined for DAs by combined gas chromatography and mass spectrometry with selected ion monitoring. The diabetic subjects had significantly (P < 0.001) more incre ased DAs excretion in urine than corresponding healthy subjects. The yields of DAs in each group decreased in the order adipic > suberic > sebacic aci d. Being stable and easily detectable compounds, DAs may be considered pote ntial markers of oxidative attack on PUFA in diabetes. (C) 2000 Elsevier Sc ience Ireland Ltd. All rights reserved.