My big toe is numb on one side, could it be diabetes?

Not necessarily: Numbness does result from a nerve function disrupted, but there are other things besides diabetes that can cause that. This includes trauma (bone or soft tissue), compression on the site as well as swelling.

Would need testing: Numbness can be an early sign of diabetes, however, there are many other reasons why a big toe is numb. There could be a pinched nerve higher up on leg or spine causing this or there could have been an injury to the big toe that caused this. If you have other symptoms of diabetes, such as thirst, frequent urination, extreme fatigue, you should see your doctor for testing.

Not sure: just numbness to the side of your big toe makes me think you have injured the nerve in that area, usually from shoes pressing against the bunion area. You should see a podiatrist for evaluation. Numbness can be a sign of diabetes but it is normally in both feet and all toes. Get checked out to be sure.