Yes Vicky, my walking almost always lowers my bg but not usually by much 0.5-1.5 at most. My fbg today was 5.1 I had 1 slice wholemeal toast (from a small sized loaf) buttered, with a cube of cheese for breakfast at 8am approx then went for an hour's walk at 9.30am my 3.9 bg was taken at approx 10.45. I have noticed, however, if I am walking really fast or running up and down stairs a lot my bg can rise for a short period before dropping again. I usually walk 2x daily for 40mins with longer walks when I'm only walking once per day. I keep to a pace where I'm slightly out of breath but can still talk as I walk. That was a long answer, sorry! Perhaps the gym is too stressful/strenuous for your BG levels? Gentler exercise should be effective. Good luck!
@ickihun