Diagnostic approaches in distal symmetric polyneuropathy in diabetes mellitus

Distal symmetric polyneuropathy (DSPN) is the most common form of diabetic neuropathy and a major cause of morbidity in patients with diabetes. Despite extensive research, diagnostic advances have been incremental rather than transformative, and accurate diagnoses in clinical practice still rely on careful clinical assessments. This review focuses on diagnostic approaches for DSPN that can be applied in routine neurological practice. We summarize the evolving definition and diagnostic criteria of DSPN, including the graded classification proposed by the Toronto consensus panel. Core diagnostic elements such as detailed history-taking, bedside neurological examinations, and validated clinical scoring systems are reviewed. We also discuss the role and limitations of nerve conduction studies, skin biopsy, corneal confocal microscopy, and tests of small-fiber function. Laboratory evaluations for differential diagnoses and current American Diabetes Association screening recommendations are also discussed.