Blood glucose increase after exercise?

I left gone a few days ago with blood glucose of 6. At 10am after soup for breakfast. Had nothing but water and tea all day. One cup of tea.

My job is quite active (delivery driver - and I tend to run around up and down drives, to doors when ladies far away etc) I came home to find my blood glucose at 5.8. I am adamant it went up to 5.8. Plus I hasn’t eaten all day?