What are other causes of neuropathy besides diabetes mellitus?

Many...: Chemotherapy/exposure to chemicals, excessive alcohol intake, some neuromuscular diseases, and many more. Sometimes the cause can't be determined and they label it "idiopathic".

Many many : I have a 2300-page 2-volume textbook in my office that details the many many causes of peripheral neuropathy. Common causes: diabetes, thyroid disease, copd, pad (vascular disease), rheumatoid and other similar forms of arthritis, certain toxins (heavy metals, alcohol, certain insecticides, agent orange), chemotherapy, certain types of cancer, vitamin deficiencies (b12, folate), & other causes.