Your blood glucose was not excessive for two hours after eating. Remember, too, that cream is not totally devoid of sugars (it contains lactose, just like milk).
You are absolutely on the right track with the exercise. I even know Type 1 diabetics who help manage their blood sugar with exercise. I realize it may be a tall order to ask a person undergoing chemotherapy to exercise, but the more we learn about it, the more clear it becomes that physical activity is essential to recovering from disease.
In Germany it is now standard practice to get leukemia patients moving within 24 hours of a bone marrow transplant. These patients are extremely weak and exercise is probably the last thing they want to do, but they start doing supervised treadmill work as soon as they can stand up. The results are better than anything that can be achieved with drugs.
You are probably capable of much more than you think, so I would try it (I speak from experience!) If you're worried about it, discuss it with your oncologist. You will probably find he or she will support you!