Clinical Presentation and Diagnostic Evaluation of Diabetic Neuropathy

Chi-Chao ChaoTaiwan Speaker Clinical Presentation and Diagnostic Evaluation of Diabetic NeuropathyDiabetic neuropathy (DN) is the most common microvascular complication of diabetes and a leading cause of peripheral neuropathy worldwide. With the global rise in diabetes prevalence, DN represents a growing clinical and public health challenge. Distal symmetric sensorimotor polyneuropathy (DSPN) is the predominant subtype, typically presenting with length-dependent sensory symptoms beginning in distal feet and progressing proximally. Patients commonly report various sensory symptoms like numbness, neuropathic pain, and imbalance. Although sensory manifestations predominate, motor weakness and autonomic dysfunction may occur and contribute to substantial morbidity, including foot ulceration, gait problem, cardiovascular and gastrointestinal complications. The diagnosis of diabetic neuropathy requires compatible clinical symptoms and signs together with objective evidence of peripheral nerve dysfunction. Large-fiber involvement is assessed primarily by nerve conduction studies (NCS), which demonstrate reduced conduction velocity and action potential amplitudes in a length-dependent pattern. However, small-fiber neuropathy often occurs early and may precede detectable NCS abnormalities. Therefore, multimodal assessment is essential. Quantitative sensory testing (QST) allows functional evaluation of thermal (small-fiber) and vibratory (large-fiber) thresholds. Skin biopsy with intraepidermal nerve fiber density quantification provides morphologic confirmation of small-fiber degeneration. Corneal confocal microscopy offers a noninvasive surrogate marker of small-fiber integrity, while heat pain evoked potentials and autonomic function tests—including QSART and sudoscan—further characterize small-fiber and autonomic involvement. A comprehensive diagnostic approach integrating clinical evaluation with complementary large- and small-fiber testing improves diagnostic accuracy, enables earlier identification of high-risk individuals, and supports timely intervention to prevent disability. This lecture reviews the clinical phenotypes, diagnostic criteria, and contemporary multimodal evaluation strategies for diabetic neuropathy, emphasizing the importance of early detection and precision phenotyping in clinical practice.