Objective To investigate the effects of repaglinide (Rg) versus gliclazide (Gli) on the levels of postprandial glucose, serum true insulin and asymmetric dimethylarginine (ADMA) in patients with newly diagnosed type 2 diabetes. Methods An open-labelled parallel studies of Rg or Gli MR was conducted on 40 newly diagnosed type 2 diabetes petients during a period of 4 weeks. Plasma glucose (PG), serum true insulin and ADMA levels at fasting and after a standard meal were measured before and after treatment with both agents. Early-phase insulin secretion was assessed using early-phase insulin secretion index (ΔI30/ΔG30). Results The effects of Rg and Gli on postprandial hyperglycemia in patients with type 2 diabetes were similar. Early-phase insulin secretion index (ΔI30/ΔG30) increased significantly in both groups (P < 0.05) and with a stroger response especially in Rg group (P = 0.018 vs. Gli). Both postprandial 240 min ADMA in Rg group (P = 0.012) and 180 min (P = 0.014) and 240 min (P = 0.002) ADMA in Gli group decreased significantly. Conclusions Treatment with Rg is associated with a greater improvement in early-phase insulin secretion. Both Rg and Gli can reduce postprandial ADMA level, which suggests the two drugs have the effect of improving epithelial dysfunction and prevention of atherosclerosis.