Introduction/Aims: Pancreatic islet transplantation (ITx) is increasingly used in patients with brittle type 1 diabetes (T1D). If successful, ITx results in insulin‐free euglycemia, but its application is limited by a need for lifelong immunosuppression. The aim of this study was to assess the long‐term effects of ITx on the occurrence and course of polyneuropathy in a cohort of patients with brittle T1D. Methods: In this prospective, single‐center study, 13 patients (4 males and 9 females) with brittle T1D had a baseline neurological exam with the calculation of Utah Neuropathy Scale (UNS) and a limited nerve conduction study before ITx, and about yearly after in the patients who achieved insulin independence. Results: Patients were followed for a period of 17 to 133 months. There was no significant difference between UNS and nerve conduction study parameters at baseline and at the end of follow‐up, except for significant decreases in peroneal (50.34 ± 6.12 vs. 52.42 ± 6.47 ms, P = 0.005) and ulnar (27.5 ± 2.15 vs. 29.45 ± 2.10 ms, P = 0.009) F‐wave latencies and an increase in ulnar sensory nerve conduction velocity (49.98 ± 6.27 vs. 47.19 ± 5.36 m/s, P = 0.04). Discussion: If successful, ITx has a good long‐term safety profile for peripheral nerve toxicity, and a favorable effect on diabetic neuropathy. [ABSTRACT FROM AUTHOR]