Objective Length dependent peripheral neuropathy is the most common complication of diabetes mellitus (DM). As no curative treatment for diabetic polyneuropathy (DMP) is available, its prevention and early detection is very important. Axonal excitability is defined as the capability of nodal and paranodal pathological changes in DMP. The aim of present study was to determine alterations in axonal excitability findings in tibial nerve by comparing median nerve axonal excitability findings in Type 1 DMP. Methods The total 284 patients, who were followed up for Type 1 DM according to criteria of American Diabetes Association, were screened in this study. Six DMP patients, 10 random non-polyneuropathy cases and 14 healthy control subjects were examined by threshold tracking method (TROND protokol) from median and tibial nerve. Results Even if there is not prominent difference in median nerve axonal excitability studies in PNP and DM patients there was prominent pathological findings in tibial nerve. The strength–duration time constant was significantly longer in DPN Type 1 patients than in normal patients. Supernormality was significantly smaller in DPN patients. Threshold electrotonus studies showed abnormalities in patients with DPN that smaller threshold changes by long depolarizing and hyperpolarizing conditioning current named as “fanning-in”. Conclusion This study confirms that there was significantly alteration in axonal excitability findings in DMP in tibial nerve. Comparisons median and tibial nerve axonal excitability findings have potential to show the length dependent polyneuropathic pathological status in axonal excitability studies.