Serum γ-glutamyl transferase is associated with plasma total homocysteine in Japanese patients with type 2 diabetes

Serum γ-glutamyl transferase (γ-GT), a marker of oxidative stress, predicts morbidity and mortality from cardiovascular disease. Plasma total homocysteine (tHcy), a pro-oxidant and also an independent risk factor for cardiovascular disease, correlates with γ-GT among some populations. It is not known whether tHcy correlates with γ-GT among type 2 diabetic patients in whom oxidative stress is increased and implicated for the development of diabetic complications. In the present study, we analyzed the association between γ-GT, tHcy and related vitamins cross-sectionally among patients with type 2 diabetes without overt nephropathy (age range 17–76 years; n = 110). In a univariate regression analysis model, γ-GT (logarithm) was positively associated with tHcy (β = 0.288, P = 0.002) but not with folate or vitamin B₁₂. The association between tHcy and γ-GT (logarithm) remained significant in a multivariate analysis model including age, lifestyle factors, folate, vitamin B₁₂, creatinine, HbA_1c and medical history (β = 0.219, P = 0.027). These results suggest that tHcy generates oxidative stress among type 2 diabetic patients and may partly explain the reported association between γ-GT and cardiovascular disease.