Nerve conduction study of medial and lateral plantar nerves in type 2 diabetes mellitus patients without sensory symptoms

Objectives: Peripheral neuropathy represents one of the most burdensome chronic complications in type 2 diabetes mellitus (T2DM), frequently evolving insidiously from asymptomatic nerve dysfunction to overt clinical impairment. Identifying subclinical neuropathy at an early stage through nerve conduction studies (NCS) may create a critical window for therapeutic intervention. The present study examined the diagnostic value of medial and lateral plantar nerve conduction parameters in T2DM patients who were neurologically asymptomatic. Materials and Methods: This cross-sectional study included 100 T2DM patients and 50 healthy controls. NCS was conducted on medial and lateral plantar nerves, and parameters such as latency, amplitude, and conduction velocity were analyzed. Clinical neuropathy was assessed using sensory neuropathy scores. Additional data on glycemic control, comorbidities, and laboratory values were collected. Results: Of 134 screened T2DM patients, 34 were excluded for abnormal Michigan neuropathy screening instrument (MNSI) scores indicating underlying sensory neuropathy. The final cohort of 100 asymptomatic patients yielded recordable plantar NCS responses in only 13; of these, 84.6% demonstrated subclinical abnormalities, with prolonged latencies constituting the most frequent finding. Absent sensory responses were recorded in 87 of the 100 patients, classified as severe abnormality and analyzed separately. Diabetic patients exhibited significantly elevated glycated hemoglobin, reduced vitamin B12, and greater body mass index relative to controls. NCS parameters, particularly latency prolongation and amplitude reduction, were markedly worse in the diabetic group. Conclusion: NCS of the medial and lateral plantar nerves is effective for early detection of subclinical neuropathy in diabetic patients. The study highlights the importance of incorporating NCS in routine diabetes care for early intervention, particularly in patients with poor glycemic control and lower vitamin B12. Longitudinal studies are needed to evaluate the progression of subclinical neuropathy and the impact of early interventions.