I see so many folks posting that the heat drops their BG, but now that we're finally having some summer sun here in Seattle, I'm noticing the opposite seems to be true for me. Anyone else notice that heat actually makes their BG higher? It could just be that more of my little beta cells are dying, but I'm hoping that's not the case.
Probably the heat! We been in low 90s with 100 % humidity and that murder with no AC! Swamp weather! Mines spiked a bit especially in the morning fasting result, .1 to .4 easily! Makes it more of a challenge forme when I go running in that sticky muggy weather! 
I have a problem with keeping my bgs down when it is hot. Lostt, do be careful when running in that weather, it is really not wise when you can dehydrate so very quickly. Make sure to run at something like 5am in the cool of the day.
I am definatly more insulin sensitive in the summer and more resistant in the winter with the cooler weater.
Can’t at 5 am! Too many muggers, druggies, and cops who might think I’m a bad dude or worth something or giving out free drugs!
I have a bunch of water fountains that I’m married too! Water water water!
This may sound silly to you but have you had your vitamin d levels checked? I was having increasing insulin needs, found out I was very low on vitamin d, got my levels straightened out and its like I'm honeymooning now.. rarely needing insulin (was only bolusing for meals) and I had been taking it for a year and a half.
When I am out in the heat too long this summer, my BG goes up into the 200's. I try not to stay in the hot temps. too long. I do drink a lot of water. We have had a very hot summer ( I live in the east), fortunately my AC has been running fine. I think my beta cells are already very dead after 13 years as a D.
I have found that when I get overheated my BG spikes super easy. I’ve looked at my patterns of food, insulin, exercise, and timing of all variables extensively and have come to the conclusion that high temps equal high BG for me. I need to be really careful with staying hydrated and I try to avoid caffeine and I can see an improvement in my numbers. I was thinking age and hormones also play a role.