Objective
To assess the possibility of phrenic neuropathy in diabetic patients, and to define the factors that influence phrenic neuropathy in those patients.

Method
Seventeen diabetic patients and sixteen controls participated in this study. The fasting and postprandial 2 hours blood sugar levels, HbA1c study, motor and sensory nerve conduction study, pulmonary function test, and phrenic nerve conduction study were examined in all subjects. The neuropathic disability score (NDS) was measured for clinical assessment in diabetic patients.

Results
1) The mean duration of diabetes was 12.3⁑7.7 years, and the mean NDS score was 3.2⁑3.8. 2) In pulmonary function test, FEV₁ and FVC of diabetic patients were lower than controls (p＜0.05). 3) The prolonged latency and decreased amplitude of phrenic nerve were shown in diabetic patients compared with controls (p＜0.05). The FEV₁ and FVC in the diabetics with phrenic neuropathy were lower than ones without phrenic neuropathy (p＜0.05). 4) The duration of diabetes, NDS are related to prolonged phrenic latency.

Conclusion
The diabetic patients with decreased pulmonary function with might be related phrenic neuropathy. The prolonged latencies of phrenic nerve were related with longer duration of diabetes and higher NDS score.