What Causes Unsteadiness And Imbalance In The Lower Part Of A Leg Apart From Tiredness While Walking?

Hello, I am 69, type II diabetic. Recently my lower leg from knee down is very undsteady and my balance is not good. When I walk I experience tiring easily as if lack of oxygen to the legs. I had a stress test a year ago and it was normal. I have some back sciatica as well. Could the balance issue be a issue with the back pain?