Note my experience is only from three months, but i have tested allot and do allot of exercise so have plenty of data points if not plenty of years at them!
The spike after strenuous exercise is not that high and usually comes down quickly. If I do a set at the gym or a run which does not tax me (I’ve I’m not really pushing) I don’t notice a rise.
If I do a very hard exercise session where I’m really sweaty and out of breath I see a rise, but still not very high (maybe from resting 5 to post exercise 6 or 7). Within 30 mins its down again to normal
As a bonus, when you exercise you stimulate your muscles which helps reduce insulin resistance so when you eat your meal your levels don’t go up as high.
Honest I don’t think you should over think it, exercise is good for you and don’t let this diagnosis change it for you. If your in the pre diabetic range, a to your diet and continue with exercise is likely to bring your results down nicely any way.
I was well in the diabetic range at 87 and i'm tacking it with diet and exercise - the benefit you get far exceeds the short spikes in my view.