Objective: To study the effects of methylcobalamin and folic acid treatment on plasma homocysteine (Hcy) level and homocysteine thiolactonase/paraoxonase (HTase/PON) activity in patients with type 2 diabetes mellitus.
Methods: 120 patients with type 2 diabetes mellitus were randomly divided into four equal groups: Group I, receiving no intervention therapy as control group, Group II, given folic acid orally (5 mg/d), Group III, receiving intramuscular injection of methylcobalamin (500 microg qd), and Group IV, treated with methylcobalamin (500 microg qd) in addition to folic acid (5 mg/d). Forty healthy age-matched persons were used as normal controls. Before and 12 weeks after 2-week treatment, plasma total Hcy, vitamin B(12), folic acid, and HTase/PON activity were assayed.
Results: After 12-week treatment the plasma folic acid and methylcobalamin, and Hcy levels decreased and serum HTase/PON activity increased significantly in the three groups receiving intervention treatment (all P < 0.05). The Hcy level decreased by 2.8% in Group I, 14.0% in Group II, 37.3% in Group III, and 21.7% in Group IV respectively (all P < 0.01). The HTase/PON activity increased by 2.7% in Group I, 8.0% in Group II, 3.4% in Group III, and 17.6% in Group IV respectively (all P < 0.05).
Conclusion: Methylcobalamin and folic acid treatment alone can decrease the Hcy level and increase the HTase/PON activity in the patients with type 2 diabetes mellitus, and the methylcobalamin and folic acid combination therapy is much more effective. Folic acid may affect the HTase/PON activity through its antioxidant ability.