Just trying to understand the difference in my blood readings when exercising

[jdolan1]

Hello!

Type 2 diabetic here since 2014

I'm just trying to make sense of some blood glucose readings. I fast all day from morning to around 6PM pretty much every day. I only drink water.

So yesterday I wake up at 8:31AM my glucose is 6.7 mmol
Then I go for a 3 mile run and check again an hour after the run, at 14:22 I'm at 6.5. Finally at 17:40 I'm at 6.0

Today I wake up and at 9:36AM I'm on 6.9
I didn't have time for a run today, so I'm at home working on my computer - little to no activity, I even had a nap in the afternoon.
At 5:42 PM I'm on 5.4

This makes no sense to me, I was hoping my blood sugar levels would shoot down after running hard for 30 mins. A lot of uphill so not an easy run.

Today I do nothing and my blood sugar goes down a lot further? Can someone please explain how this works?

 

[Leadinglights]

Hello!

Type 2 diabetic here since 2014

I'm just trying to make sense of some blood glucose readings. I fast all day from morning to around 6PM pretty much every day. I only drink water.

So yesterday I wake up at 8:31AM my glucose is 6.7 mmol
Then I go for a 3 mile run and check again an hour after the run, at 14:22 I'm at 6.5. Finally at 17:40 I'm at 6.0

Today I wake up and at 9:36AM I'm on 6.9
I didn't have time for a run today, so I'm at home working on my computer - little to no activity, I even had a nap in the afternoon.
At 5:42 PM I'm on 5.4

This makes no sense to me, I was hoping my blood sugar levels would shoot down after running hard for 30 mins. A lot of uphill so not an easy run.

Today I do nothing and my blood sugar goes down a lot further? Can someone please explain how this works?

Welcome to the forum.
Exercise seems to be one of the things that can cause much variation between people, for some exercise leads to blood glucose going down for other it goes up as the liver releases glucose to give people the energy for organs and muscles to function.
Also in the absence of food the liver does just that which is why some people experience their highest readings of the day in the morning after fasting over night.
There are a few threads about the effect of exercise. It can also depend on what meds you are taking and what dietary regime you follow.

 

[rebrascora]

This makes no sense to me, I was hoping my blood sugar levels would shoot down after running hard for 30 mins. A lot of uphill so not an easy run.

The above is important information to consider when you are looking at how exercise impacts your levels.
It depends on how fit you are and how much that exercise stresses the body. Prolonged steady exercise like a brisk walk will usually reduce your levels whilst you are doing it. Mine start to drop after about 40 mins and can drop by 2 or 3mmols over a 2 hour walk, but if I run up a steep hill which makes my muscles burn and my heart race and my lungs get a good work out, then my levels will start to rise because this is putting my body under strain which causes my liver to release glucose into the blood stream. You are also exercising whilst fasting and again, this will cause your liver to release extra glucose. I don't know if it is the same for people who are not injecting insulin but exercising after a meal when I have injected insulin for the meal, will cause my levels to drop much more significantly than if I exercise before a meal ie fasting. However, I imagine that if you are Type 2 and have a fatty liver, this release of glucose from the liver will help to deplete it's stores and make it less fatty.
The other thing to know is that exercise can impact our levels for up to 48 hours afterwards, so it is likely that your run yesterday was responsible for your lower readings this afternoon, when your muscles were replenishing their stores whilst you were more sedentary. I find that for me it happens overnight as soon as I go to sleep and my levels drop significantly after exercise that day. Also, I think I have read that the more muscle you develop, the more storage space you have for surplus glucose, so that enables your body to process the glucose in your blood more effectively and store it where it can be used instead of hanging around in your blood causing problems.

It might be worth doing some experimenting with exercising before and after food, to see which gives you the best results, but do bear in mind that the beneficial effect can take up to a couple of days to run it's course.

Basically, there is more or less real time benefit in steady aerobic exercise, but once you get into anaerobic exercise where the body is stressed, levels may well; go higher initially but there will be longer term gain from that exercise.

 

[harbottle]

Recently, I watched a TV show where they got the presenter to do a short run and tested her blood before and after.

It had risen from the fives to the sixes.

The body releases adrenaline which causes blood sugar to rise. It's perfectly natural part of the 'fight or flight' response.
It's totally normal.

 

[jdolan1]

Thanks. Yes makes a lot of sense. So today at 11:03AM I was on 6.3, then went for a 4 mile easy walk and at 15:13 two hours after the walk I'm on 5.6.

 

[helli]

The body releases adrenaline which causes blood sugar to rise. It's perfectly natural part of the 'fight or flight' response.
It's totally normal.

I wish it was this simple but a run can also cause BG to fall under certain scenarios. In fact, falling BG is most common for cardio unless you are doing interval training and, if a non-diabetic person kept going without "fuelling" it would lead to "bonking".

The way I understand it is that adrenaline is an insulin inhibitor so as your body detects the BG falling, it may release adrenaline in order to reduce the insulin and stop the BG drop.
The other thing the body may do when it notices you are using lots of glucose is to do a "liver dump" which will also increase BG.
However, over time, this is counteracted by the muscles using up the glucose.

So, a shorter exercise will see BG rise and a longer exercise will see BG fall. Unless ...
as @rebrascora illustrates, the body is stressed (e.g a tough or uncomfortable run) in which case the liver will continue with its dump.

I often illustrate this with my cycling
- a pootle along a flat tow path on a pleasant day while chatting to friends will have little impact on my BG
- a short fast sprint will raise my BG
- a 45 minute full on indoor (unaffected by weather) Spin class will cause my BG to plummet
- a long crawl uphill against the wind in the rain in "granny gear" will raise my BG.

 

[JohnS]

If I do a relatively hard run my BG will first go high and then crash down about a half hour later. If I just go for a gentle trot or brisk walk my BG drops steadily but not drastically. As @harbottle says, it’s the flight or fight response. Stress can also cause it to go high as in driving, etc.