Peripheral nerve enlargement in patients with diabetic sensorimotor polyneuropathy: A systematic review and meta-analysis

This study aimed to summarize evidence on peripheral nerve enlargement in patients with diabetes, with and without diabetic sensorimotor polyneuropathy (DSP), compared with healthy controls. PubMed and Embase were systematically searched for ultrasound studies measuring the cross-sectional area (CSA) of peripheral nerves in patients with diabetes with and without DSP. The primary outcome was the weighted inter-group mean difference in CSA at all reported upper- and lower extremity sites. Forty-seven studies were identified, of which 41 were included in the meta-analyses. Patients with diabetes without DSP showed significantly larger CSA values than healthy controls at 3 of 11 anatomical locations, all located in the lower extremity. Patients with diabetes and DSP demonstrated increased CSA compared with controls at 9 of 14 sites, particularly at distal compression sites of the median and tibial nerves. Compared with patients with diabetes without DSP, those with DSP had significantly larger CSA values at 14 of 21 sites, with the greatest difference observed 4-5 cm proximal to the medial malleolus (pooled mean difference + 5.26 mm², 95% CI 0.94-9.57). In conclusion, peripheral nerve CSA is increased in diabetes and further enlarged in the presence of DSP, with the largest effects at distal compression sites.