Folic acid is very important for diabetic patients. Folic acid is a vitamin that helps prevent and treat diabetic peripheral neuropathy. Diabetic patients are often in a high blood viscosity state and have very high homocysteine. Normally, homocysteine should be below 10umol/L, but most diabetic patients are above 20umol/L. Increased homocysteine is very susceptible to cerebrovascular disease, especially cerebral thrombosis is more common. Diabetic patients taking folic acid can reduce the risk of cerebrovascular disease by lowering homocysteine. Diabetic patients with a homocysteine level above 15umol/L on routine laboratory tests should take regular doses of oral folic acid.