Diabetic sensorimotor polyneuropathy (DSP) is the most common complication of diabetes. In order to manage DSP effectively, it is necessary to formulate an accurate diagnosis and monitor subjects regularly. This review of important aspects of the diagnosis of DSP starts with a conceptual framework that includes elements of DSP epidemiology, pathophysiology, and therapy. The emphasis of the review is to present our current understanding of diagnostic methods for DSP including their utility and limitations. Screening for DSP in the diabetes clinic can be achieved successfully using simple clinical tests. Clinical neurophysiological methods are necessary to exclude other diagnoses, stage severity, and monitor the course of DSP. Novel investigative techniques are highly promising, but their usefulness in the clinic setting remains limited at this time. This article presents an overview of diagnostic methods for DSP.