My diabetic obese friend has foot pain and some numbness. is it ok for him to use a menthol gel like biofreeze (2-4%) menthol, on his feet ?

Control risk factors: Menthol is ok but it is only treating the symptom. Your friend needs to treat the cause of the foot pain/numbness which in a diabetic is a signal for neuropathy. He needs to control his blood sugar level, blood pressure (circulation) and cholesterol levels. Good luck.

Yes: Biofreeze is ok to use but your friend should probably esamined by a podiatrist to see about the pain & numbness.

Maybe: If the skin is closed it should be ok. The problem is its unlikely to help.

It may help.: It may be of benefit in some cases.