F-wave is useful in the evaluation of proximal segment of peripheral nerve which is inaccessible to conventional nerve conduction study, because it is believed to result from antidromic stimulation of motor nerve fibers. The purpose of this study is to determine the diagnostic usefulness of three F-wave parameters in patients with diabetes mellitus.

The average F-wave latency(F-mean), the minimal F-wave latency(F-min), and the minimal-to-maximal latency difference of F-wave(F-range) were evaluated in 60 normal healthy subjects(male 39, female 21) and in 20 patients(male 14, female 6) with diabetes mellitus. The values of F-mean and F-min were significantly prolonged in patients with diabetes mellitus in both ulnar and tibial nerves(p<0.01). The value of F-range in diabetes mellitus was significantly prolonged in tibial nerve(p<0.05). These three F-wave parameters may be a sensitive method in the early detection of possible diabetic neuropathy when conventional sensory and motor conduction studies are normal in the face of clinical evidence.