Diabetic patients are prone to deficiencies of B vitamins, vitamin C, vitamin D and a variety of micronutrients such as chromium, zinc, selenium, magnesium, iron and manganese, which can be supplemented in appropriate amounts according to the results of nutritional assessment, but long-term, large amounts of vitamin E, vitamin C and preparations with antioxidant effects such as carotenoids are not recommended for diabetic patients. Among them, diabetic patients taking metformin for a long time should prevent vitamin B12 deficiency and can take appropriate supplementation. Medical nutrition is the basic treatment for diabetes. Individualized nutritional assessment, nutritional diagnosis and nutritional intervention for diabetic patients are necessary to ensure blood glucose and nutritional stability.