Objective
The purpose of this study is to find out whether amplitude ratio and area ratio have correlation with nerve conduction velocity in the diabetes mellitus patients.

Method
Median and deep peroneal motor nerve conduction study was performed in thirty-five normal control group and sixty diabetes mellitus patients group. The motor conduction velocity, amplitude ratio, and area ratio of the compound muscle action potential (CMAP) were measured. The experimental subjects were divided into 6 subgroups (in median nerve: M1, M2, M3, in peroneal nerve: P1, P2, P3) according to the median value of conduction velocity of each nerve; group M1 (n=35) and P1 (n=30): normal control group, group M2 (n=25) and P2 (n=30): below the median value of motor nerve conduction velocity in diabetes mellitus patients, group M3 (n=23) and P3 (n=29): above the median value of motor nerve conduction velocity in diabetes mellitus patients.

Results
There was no significant difference of area ratio between the each subgroups in both median and peroneal nerves. There was a significant difference of amplitude ratio between the M1 and M2 subgroups. There was a significant difference of amplitude ratio between the P1 and P2, P3 subgroups.

Conclusion
According to above results, the decrease of amplitude of compound muscle action potential along with the decrease of conduction velocity seems to be helpful in the electrophysiologic diagnosis of diabetic neuropathy.