I finished up about half an hour ago doing some bike sprints and weight lifting fasted. my blood sugar has gone up about 20 points so far. do normoglycemic people have this reaction? what causes blood sugar to go up after exercise when you have nothing in your stomach?
PS I control blood sugar through diet and exercise alone. the highest my A1c has been that i know of is 5.9
My personal experience is that anaerobic exercise like sprints or weight lifting raise my blood sugar. The explanation I have seen is that this sort of exercise releases cortisol and adrenaline and that causes a rise in blood sugar. Before I started insulin I would routinely see my blood sugar soar over 100 mg/dl during workouts. After I started insulin I would take some insulin before working out in order to maintain normal blood sugars.
I actually found this effect could be used to systematically keep my blood sugar stable. Aerobic exercise tends to drop my blood sugar. I could put together mixed routines of aerobic and anaerobic exercise to keep things stable. You can do this with mixtures of interval training or by splitting up your lifting with cardio sessions.
Yes , the body notices that the body is using more energy but is programmed to think that the pancreas is still producing the required amount of insulin so the body gets too much energy out of storage so the bgl goes up. Type 1s who are long term sufferers the body also attacks the alpha cells on the islets of langerhanes which produces glucagon to raise the bgl by instructing the liver to release glucose to raise the bgl , hence the risk of a type 1s bgl plunging. I will swap your type 2 for type 1 if you prefer!
i’m not any type yet. so far so good.
Actually, my understanding is the autoimmune T1 is solely an autoimmune attack focused on beta cells. When you have T1 your alpha cells still produce glucagon but you have a messed up regulation of glucagon production and release. If you have a source for the idea that alpha cells are destroyed by the beta cell autoimmune attack I’d be very interested.
I have a friend with type one, who when going low, routinely “treats it” with 20 push ups! The adrenaline/cortisol realeased works to raise his blood sugar sufficiently! So interesting!
If only I could do 20 push-ups!! 
It depends upon the type of exercise, the duration of exercise and the fitness level of the exerciser. If I walk for forty minutes at a pace commensurate with my fitness level ↓, if I go at a pace above my fitness level ↑↑, then ↓↓ later.
And when my Type 1 is gas-lighting me: →, ↑ or ↓ are all possible.
If you are early in your type 1 you still have enough cells in the islets to produce enough glucagon to make it easy to control - the so called Honeymoon period but eventualy the imune system attack on both the alpha and beta cells (Alpha - gucagon wich raises bgl & beta - insulin wich lowers bgl ) on the islet’s of Langahans so you can neither lower or raise the bgl by the standard methods so life becomes interesting . the imune response is first on the beta cells because there is little glucagon in early phases of the “Disease” and when you start on insulin Everyone has a tendincy to overdo the insulin so the response is more pronounced production of glucagon to counteract the user’s control action hence bouncy bouncy overshooting until you get it more or less right ! relax
The general rule (“general”, I said, not absolutely universal) is that aerobic exercise simultaneously reduces insulin resistance and lowers blood sugar, whereas anaerobic exercise elevates blood sugar.
I discovered this with snow shoveling my first winter after diagnosis. Scopping up light snow (we have a lot of sidewalk and a wide, short driveway) generally lowers my BG (like a brisk walk does) whereas dealing with a lot of wet heavy snow causes my BG to drop at first, then go up (strength training). I over-corrected in a big way with the first storm but now with my CGM I see the whole dynamic! 
️:snowflake:️
My BG definitely goes up during intense exercise (sometimes as much as 30 to 50 mg/dL), and then can drop low after I’m done. I think of this in terms of what others have said: cortisol and adrenaline are released due to physiological stress and BG goes up quickly; after exercise, hungry muscles soak up all the free blood glucose they can get, and my BG drops quickly.
The trick for me has been getting the timing right on treating the moderate lows I get from endurance sports and exercise. I have yet to go skiing this winter because I’m concerned about the lows: hiking and cycling have gotten me into the low 50s, and although I’ve got the solution figured for those activities, I’m not sure what I’ll need to do for skiing. But, hopefully next week I’ll take the dogs and the skis and my meter and some quick carbs out to the trails and find out!
What is really cool and fun - if you have access to a treadmill or stationary bike, a bunch of test strips, and a lot of patience to repeat the experiment - is to find that zone! To me, it was great to find exactly what running pace makes my BG start to rise.
It does make a difference. DHF’s annual Big Blue Test is designed to spread the awareness and provide motivation to exercise by demonstrating on an individual basis how much it can actually help.
in the early stages of the attack it only atacks the beta cells - probably because of the “C” peptide that is cleaved to make the final version of insulin so it attacks the Beta cells. The alpha cells in a “Normal” person are very inactive unless you have an insulin secreting tumor which comes into play to protect you from going too low. wear as when you start on insulin you are up and down like a yoyo (stupid usless users) so the imune t cells learn to target glucagon (alpha cell product) as well dum imune system thats why there is the “honeymoon” period , Designer stuffed that one up!
The explanation I got for BG rise during upper body routines had something to do with short muscle fibers and their energy requirements and my own insulin resistance issues - my liver is just a little too helpful!
A 20 point difference can also simply be due to variance in the BG meter. I can test from the same drop of blood, on same meter and sometimes less than 10 pts, and other times 30 or more points difference.