I do not share your uncle's situation – I was diagnosed at age 32 with MS, do not have diabetes, have never had chemo or radiation; I have quite different ideas about MS from most other people. I suspect that excess insulin plays a big role in MS. With that belief, I suspect that your uncle has type II diabetes, which also has elevated insulin levels. I encouraged him to ask his doctor for a "fasting serum insulin test" – this is not the same as a glucose test. For the insulin test, a result above 7 UU/ML is elevated.
Since I no longer believe that MS is "an autoimmune disease," I no longer take any of the injectable MS drugs designed for autoimmunity. (Through the years I have tried three of them, but never saw a benefit. In fact, the side effects were intolerable.)
I think the greatest improvement can be achieved with a no carb (or at least very low-carb) diet. Carbohydrates are not necessary for a healthy diet; they convert to glucose (blood sugar) in the bloodstream and trigger insulin production. Low-carb veggies, such as kale, Swiss chard, broccoli, etc., are acceptable, but not the starchy vegetables. Protein and fats are vital to the diet – vitamins are made from the amino acids in them, fat is even necessary for the insulation for the nerves, which are targeted in MS.
Google. "Dr. Terry Wahls" and read about her great success overcoming MS with diet and exercise.
Best wishes to your uncle.