Glyoxalase system in clinical diabetes mellitus and correlation with diabetic complications.

1. The metabolism of methylglyoxal by the glyoxalase system may be linked to the development of diabetic complications. The glyoxalase system was characterized in blood samples from patients with insulin-dependent diabetes mellitus (n = 43), patients with non-insulin-dependent diabetes mellitus (n = 107) and 21 normal healthy control subjects. 2. The concentrations of glyoxalase metabolites, methylglyoxal, S-D-lactoylglutathione and D-lactate, were increased in diabetic patients, relative to normal control subjects: methylglyoxal [median, range (n) pmol/g], insulin-dependent patients, 470.7, 85.6-1044.3 (42), P < 0.001, non-insulin-dependent patients, 286.8, 54.7-2370 (105), P < 0.001, control subjects, 79.8, 25.3-892.9 (21); S-D-lactoylglutathione [mean +/- SD (n)pmol/10(6) erythrocytes], combined diabetic patients, 3.37 +/- 0.85 (24), control subjects 4.76 +/- 1.95 (8) P < 0.05; D-lactate [mean +/- SD or median, range (n)nmol/g], insulin dependent patients, median 18.3, 5.7-57.4 (42), P < 0.001, non-insulin-dependent patients, 20.0 +/- 8.9, 2.6-48.4 (105), P < 0.001, control subjects 9.7 +/- 4.3, 1.8-19.7 (21). The reduced glutathione concentrations in blood samples from the insulin-dependent and non-insulin-dependent diabetic patient groups were not different from the control group values (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)