Effects of hot weather on sugar levels.

I have been checking my glucose levels at home with accucheck once a week, where I make a point to check them fasting, random and postprandial on the same day.
One day I managed to record reading for BG immediately after coming home, after spending hours under hot sun without cap on, sometime, around 1pm, my BG was found to be 230. Shocked I rested at my home for an hour had a glass of water and checked again it was found to be 150.
I repeated the procedure several times on other days to rule out error and it was same pattern all the time.
Then I realized that after moving under hot sun without cap on, some how BG shoots up and reverts back to otherwise normal after resting in shade for over an hour.
Therefore some guidance is required on this, whether direct and sustained exposure to hot sun is causing it and whether it is to be avoided for diabetics, as in my opinion can create stress like situation.

 

I stay in India, a hot tropical country and as civil engineer forced routinely to stand and travel on bike in hot sun to supervise and not to actually work. The observations were by chance as I attempted taking random BG almost immediately after coming from such exposure with absolutely no food intake after breakfast (4 hours fasting ). BG was even found as high as 256 and returned back to below 160 on its own without any intervention except a glass of water sometimes.( prior fasting BG was within 130 on same day) I did not wear cap earlier and hardly hydrated myself. But I will do it and post the results immediately.
My normal readings are 130 fasting, 150 PP and 150 random with normal exposure. (latest A1C 7.2), with reasonable diet and 1 tablet of 500 mg metformin SR at breakfast. Also my diabetes is hereditary all my siblings(total 4) male & female have it, probably inherited from our mother..