Objective To discuss the relationship between hyperhomocysteinemia(HCY) and chronic complications in type 2 diabetes.Methods 206 cases with type 2 diabetes were divided into no microvascular complications(NDC) group,diabetic retinopathy(DR) group and diabetic nephropathy(DN) group according to the occurrence of microvascular complications,98 healthy persons were selected as control group.The levels of plasma HCY,folic acid(FA) and vitamin B12(Vit B12) were detected by chemiluminescence method.Results Plasma HCY in diabetic group was significantly higher than the control group (P ＜ 0.05 ),DMAP group (DR group and the DN group) was higher than the NDC group ( P ＜ 0.05 ),FA,Vit B12 levels were significantly decreased compared with control group(P ＜0.05 ).Statistical analysis showed that HCY level was negatively correlated with FA,Vit B12 levels in patients with diabetes( P ＜ 0.01 ).Condusion HCY is an important risk factor for DMAP,the determination of plasma HCY level in patients with diabetes will help to monitor,determine the occurrence and development of DMAP.