Diabetic peripheral neuropathy and cognitive impairment， as the neurological complications of diabetes， often occur in diabetic individuals at the same time， and seriously affect the quality of life of diabetic patients. The two manifested as diabetic peripheral and central nervous system diseases respectively. The traditional view is that the two are independent diseases. At present， more and more evidences show that there is a significant correlation between diabetic peripheral neuropathy and cognitive impairment. The pathophysiological mechanisms of the two have many things in common， and the two have many common biological markers. This article reviews the clinical manifestations and electrophysiological manifestations， pathophysiological mechanisms， pathological changes， and biological markers of peripheral nerve and cognitive impairment in diabetic patients to further illustrate the relationship between the two.