Diabetic polyneuropathy is a complex disease of progressive nerve fiber loss. Initial screening and diagnosis in clinical practice usually depend on assessment of subjective complaints. A need exists for objective, simple, and reproducible assessment tools that can be readily used in clinical practice. The importance of early diagnosis is highlighted by the recent North American Diabetes Control and Complications Trial where intensive insulin therapy reduced the risk of developing diabetic neuropathy by 61%. At the University of Michigan, we have developed an outpatient neuropathy program. Patients are given a questionnaire and a brief screening examination, designated the Neuropathy Screening Instrument. Diabetic neuropathy is confirmed and staged in patients with a positive Neuropathy Screening Instrument, by a quantitative neurologic examination and nerve conduction studies, designated the Diabetic Neuropathy Score. The Michigan program has been compared with well-established instruments and has been found to be sensitive and reproducible for screening and diagnosis. We believe the program provides a valuable tool for the clinician in the practice setting and should allow diagnosis and intervention earlier in the course of diabetic neuropathy.

Electrophysiological studies are a reproducible and noninvasive method of assessing peripheral nerve function. The sensitivity of these methods has been validated in population-based and clinical studies, and the variability of test results is typically lower than with other noninvasive tests of nerve function. It has been recommended that standardized procedures including temperature control and equipment calibration be utilized with electrophysiological testing. The failure to detect significant changes in nerve conduction studies from clinical studies may be due to poor standardization of technique and inadequate sample size to detect differences. Baseline results from a multicenter, randomized trial indicate that different electrophysiological measures are highly correlated and reproducible. This and future studies that incorporate standardized techniques and an adequate sample size should be able to detect significant differences between treatments and identify effective therapeutic interventions for diabetic neuropathy.

Diabetic neuropathy is a major complication of diabetes mellitus affecting to an equal extent type 1 and type 2 patients. Various mechanisms including metabolic and vascular abnormalities have been proposed to explain the progressive pathological changes that occur in peripheral nerve. Regardless of the precise mechanisms, structural abnormalities lead to functional changes which eventually result in the clinical manifestations of diabetic neuropathy. Possible interventions that may influence the progressive disease process include intensive insulin therapy and aldose reductase inhibitors. This article reviews the proposed pathogenetic mechanisms underlying diabetic neuropathy, their effects on nerve histomorphometric changes and ultrastructure typical of diabetic neuropathy, and potential therapeutic interventions and their impact on disease progression.

Diabetic polyneuropathy is a major complication of diabetes mellitus that frequently leads to foot ulceration. Because of economic impact of foot ulceration and subsequent amputation, major initiatives are under way in the United States and the United Kingdom to reduce their incidence by up to 50%. Although diabetic ulcers may have an ischemic and neuropathic component, the majority are neuropathic. Results from studies have shown a strong association between the neuropathy and the subsequent development of foot ulcers. However, other predisposing factors such as high foot pressures, inappropriate footwear, and other extrinsic pressure usually must be present, together with neuropathy, to cause foot ulcers. Therefore, the challenge to the physician is to identify the patient at risk and intervene so as to educate and prevent the occurrence of foot ulcers.