This article may be of interest. Seems to explain some of the reason why exercing with T1 can be challenging.
We always have slightly elevated insulin levels. This insulin is reducing the glycogenolysis - the conversion of glycogen from the liver to glucose. As a result the article shows that:
The counter regulation against lows does not work for us. Even the little background insulin from the basal does prevent that. With sporty activity we will need small boosts of glucose to keep the level of blood glucose. Even this small reaction - in comparison to fighting lows - seems to suffer from the impaired glycogenolysis.
It is good that the article is also stressing that insulin is needed in the equation. This makes cutting back the basal with the pump a fine balancing act. Too less is not benefitial for our health. Too much and we have to add carbs as our only chance to have glucose available. Since I am on MDI I am always on the carb fueling side and I have developed my strategies to handle sports - of course with the usual imprecisions of life and the mistakes we all make from time to time.
I found it odd that they claimed: "Exercise is not a tool for improving blood glucose control in type 1 diabetes".
I think this is wrong because: the more active > the more muscle mass > muscles in inactive state will consume more fat (higher metabolic rate) > the less fat the more sensitive to insulin > muscle mass will act like a buffer that will consume excessive glucose to some degree. These effects are VERY benefitial for type 1 diabetes.
I was going to write about that sentence too. Taken out of context it is odd. But if you read it in context, the surrounding sentences do summarize the benefits of exercise pretty well.
I think that sentence was put in there, to counter those who might think that exercise alone (no insulin) can treat T1 diabetes. Trust me, I know a lot of people who believe that the right exercise and good intentions would cure me :-)
Like my boss OMG! She signed me up for a 5K and told me that I should take up running like her and aim to run marathons so I won't have to inject because she read that exercise lowers your BG o_O
As a very active T1, I have found the key to managing T1 while exercising is identifying patterns and adjusting carefully and accordingly. For example, there are many kinds of activities that, for me, cause a rush of adrenaline and therefore require MORE insulin. Some activities require a reduced basal rate, some don't. Some activities require a reduced basal rate ONLY if they are undertaken in extreme heat and/or for prolonged periods of time. I have found that if I carefully track the results of each excursion and what I did/didn't do (i.e., reduce basal rate, consume carbs, etc), I can usually end my exercise somewhere in the 80-200 range. Sometimes this doesn't happen, and this means figuring out what I can tweak for the next time.
For me, it has always been a lot of tracking, logging, tweaking, and repeating until I get it right.
The muscles will release their glucagon stores with anaerobic exercise. Thus these anaerobic conditions can trigger huge spikes.
There are significant internal stores of glycogen in your muscles. During exercise, these stores can be immediately used for energy, but they cannot be released into the blood stream. The blood sugar rise is entirely due to gluconeogenesis in your liver.
Personally, I feel that exercise is a great tool for improving blood sugar control, it not only increases insulin sensitivity but ongoing activity means that your blood sugar has a place to go rather than sitting around just keeping you "high." And strong people are harder to kill and more generally useful.
I agree with you! Especially about strong people.
In my understanding the liver is the only place to convert glycogen to glucose. Thus the muscles will release the glycogen stores. The liver will convert the glycogen to glucose, which will cause the blood glucose to spike. Then insulin is needed to transfer the glucose back into the muscle from the blood stream. At least this is how I understood the mechanics from page 171 and following in 'Your Diabetes Science Experiment' by Ginger Vieira.
Yes, the liver is able to break down stored glycogen and able to release glucose into the blood stream. The glycogen stored in muscles can be converted to glucose, but as noted in wiki "Muscle cells lack the enzyme glucose-6-phosphatase, which is required to pass glucose into the blood, so the glycogen they store is destined for internal use and is not shared with other cells."
I think that the thing we're overlooking is that it's kind of recommended for "straight" athletes without diabetes to have carbs for big workouts too? The Chicago Marathon has something like 17 aid stations, some of which stretch for 1/4 mile so there'd be > 4 miles of Gatorade strewn along the course? I'd like to think that it was all for my benefit but saw plenty of people hitting the sauce!
My experience has been that I don't think I 'need' quite as many carbs as are "recommended" and that I seem to have better runs if I can balance my BG rather than going up and running it down and going up and running it down? It's tricky but it's part of the challenge and gives me a great feeling of success when I come home and my BG is 85 and I've had a good run? I get a bump, maybe 20-30 points from lifting so I try to start that lower and I usually try to do 20-45 minutes of elliptical when I'm done lifting to "eat" whatever boost the lifting provides.