Should you exercise with high blood glucose?: "Exercise management in type 1 diabetes: a consensus statement" from The Lancet.

[SimonP]

I've pulled this post out of the thread I originally posted in as it was suggested it might benefit people by being more visible.

I read a fair number of threads with people saying that one should not exercise when high as it's not good for you (or words to that effect). I understand that DAPHNE courses may also be discouraging people from exercising while high.

As far as I understand the only issue with exercise while high is that it may increase your BG (any exercise may increase BG, depending on the intensity of the exercise) and if you're high you may also have ketones (which are not caused by being high, but are a side effect of too little insulin, which also makes you go high), you may therefore generate more ketones and potentially suffer from ketoacidosis.

I do feel this is perhaps blown out of all proportion though, especially as most people will have some basal insulin floating around.

If anyone has any links to any papers/guidance that indicates that there are other issues with exercise while high, please post, and I'll think about changing my opinion! 🙂

Edit/addition: For clarity, while (typically high intensity/anaerobic) exercise can increase BG initially, afaiu it depends on how the liver reacts to the level of exercise i.e. how much stored glycogen it converts to glucose to "help" you on the way, eventually the increase stops and BG will decrease (you run out of stored glycogen after an hour+ or more likely your adrenal response subsides more quickly than this as you become used to the activity - these are my supposition though based on experience rather than research). So basically it's not all bad even if BG does start to rise with exercise, and it doesn't always happen: if you are used to the exercise or exercise at a lower intensity.

I have no qualms about exercising when high, though I tend to ensure I have at least a little bit of (bolus) insulin on board if I'm properly high or heading upwards (like 15mmol/l+). A steady 10 mmol/l & exercise will probably drop me through the floor so no insulin required (aside from my basal, which is already there). I would certainly be more than happy to exercise with a blood glucose of >15mmol/l, though I would certainly be trying to work out why I'm high as well as fixing the problem - not taking enough bolus to cover DP before exercise often gets me, or it could be mistiming insulin/meal or misjudging carb content. Obviously care should be taken if you have a full meal's worth of IoB (e.g. if you weren't planning to exercise), as exercise will make it very potent, the same is true of taking a full correction dose and then doing exercise.

In the "Exercise management in type 1 diabetes: a consensus statement" published in the Lancet (the paper is free to access: https://pubmed.ncbi.nlm.nih.gov/28126459/ or doi: 10.1016/S2213-8587(17)30014-1) they say that levels between 10.1 and 15mmol/l are fine, though that blood glucose may rise; for levels above 15 mmol/l they say that ketones should be monitored if the high blood sugar is not due to recent food. If ketones are normal then they say to continue to monitor; if ketones are slight elevated, only do short duration low intensity exercise; if ketones are high treat with insulin and don't exercise.

Here is the actual text:

Blood glucose concentrations before exercise commencement and recommended glucose management strategies
The carbohydrate intakes shown here aim to stabilise glycaemia at the start of exercise. Blood glucose at the start of exercise must also be viewed within a wider context. Factors to consider include directional trends in glucose and insulin concentrations, patient safety, and individual patient preferences based on experience. Carbohydrate intake will need to be higher if circulating insulin concentrations are high at the onset of exercise.
Starting glycaemia below target (<5 mmol/L; <90 mg/dL)

• •
  Ingest 10–20 g of glucose before starting exercise.
• •
  Delay exercise until blood glucose is more than 5 mmol/L (>90 mg/dL) and monitor closely for hypoglycaemia.

Starting glycaemia near target (5–6·9 mmol/L; 90–124 mg/dL)

• •
  Ingest 10 g of glucose before starting aerobic exercise.
• •
  Anaerobic exercise and high intensity interval training sessions can be started.

Starting glycaemia at target levels (7–10 mmol/L; 126–180 mg/dL)

• •
  Aerobic exercise can be started.
• •
  Anaerobic exercise and high intensity interval training sessions can be started, but glucose concentrations could rise.

Starting glycaemia slightly above target (10·1–15·0 mmol/L; 182–270 mg/dL)

• •
  Aerobic exercise can be started.
• •
  Anaerobic exercise can be started, but glucose concentrations could rise.

Starting glycaemia above target (>15 mmol/L; >270 mg/dL)

• •
  If the hyperglycaemia is unexplained (not associated with a recent meal), check blood ketones. If blood ketones are modestly elevated (up to 1·4 mmol/L), exercise should be restricted to a light intensity for only a brief duration (0 min) and a small corrective insulin dose might be needed before starting exercise. If blood ketones are elevated (≥1·5 mmol/L), exercise is contraindicated and glucose management should be initiated rapidly as per the advice of the health-care professional team.
• •
  Mild to moderate aerobic exercise can be started if blood ketones are low (<0·6 mmol/L) or the urine ketone dipstick is less than 2+ (or <4·0 mmol/L). Blood glucose concentrations should be monitored during exercise to help detect whether glucose concentrations increase further. Intense exercise should be initiated only with caution as it could promote further hyperglycaemia.

 

[MikeyBikey]

I was told, around 20 years ago, nothing more than walking if 15 or over, and none if 20 or over, as the risk of a clot increases. Frequently that sort of level is due to infection and then I feel making a cuppa is enough exercise!

 

[helli]

I don't necessarily consider it dangerous.
It is more that it is often suggested to use exercise to lower high BG. As you mentioned, it can do the opposite.
So my concern is the suggestion to "go and do some exercise" if your BG is high. It is not a guaranteed solution. For those of us with Type 1, insulin is a more reliable solution.

 

[everydayupsanddowns]

Thanks @SimonP that’s really interesting.

I think I had ‘don’t exercise if BG is in the teens or higher’ in my head, but this makes much more sense, and is much more precise.

 

[SimonP]

I was told, around 20 years ago, nothing more than walking if 15 or over, and none if 20 or over, as the risk of a clot increases. Frequently that sort of level is due to infection and then I feel making a cuppa is enough exercise!

Interesting, can I ask who told you (GP, diabetes team, etc.)? I didn't see this mentioned in the (more up-to-date) consensus statement, nor have I seen any publications highlighting this as being a risk, but your view is held by others and I often read similar sentiments expressed on the forum.

The BG threshold values/exercise levels do roughly correspond to those in the consensus statement (assuming that most people in the population don't actually do much exercise - so a walk could well be classified as moderate exercise for them). But the concern in the consensus statement is due to ketones not blood clots. Perhaps this is a change in the understanding of the effects of high BP from the diabetes/medical profession, or it may be that those BG numbers are easy to remember so make decent thresholds for whatever advice is being given. If anyone has any literature providing a link (to blood clots or other deleterious side-effects that are not ketone-related) I'd be interested to read it.

I assume that if exercising with high blood glucose did indeed risk this to any significant extent, one would see lots of T2s (un-diagnosed or poorly controlled), as well as those T1s who do exercise while high (or who are recently diagnosed, or poorly controlled), dropping like flies.

I agree that usually high levels are typically due to being ill and then one doesn't fancy exercise anyway, though even then a short/gentle walk can be helpful in my experience - it doesn't take much activity to improve insulin sensitivity (though I am now straying into personal experience without data to hand/literature to back it up, so strike that one from the record! 🙂)

I don't necessarily consider it dangerous.
It is more that it is often suggested to use exercise to lower high BG. As you mentioned, it can do the opposite.
So my concern is the suggestion to "go and do some exercise" if your BG is high. It is not a guaranteed solution. For those of us with Type 1, insulin is a more reliable solution.

I understand what you're saying and if there had to be a choice of one or the other, then insulin would obviously win.

I agree that if someone says "Just go and do exercise" it requires more nuance, I hope I've not ever given that impression.

Some people, such as myself, can suffer from highs which linger, presumably because of higher insulin resistance at high BG levels meaning that much more insulin is required than is typically the case. I find taking some correction plus doing exercise (even a 10min walk, I'm not talking about needing to do multi-hour bike rides) is much more effective to bring high blood sugars down more rapidly - though care must be taken, as not much correction bolus is needed once exercise is added to the mix.

 

[rayray119]

When I did DANFE course it was sujuested to have your levels between 7 and 15 but I don't think in my case before it's been a partner problem before. I think in the think like parncaus book he says excise can be done above 15 as long as you have no ketones and a correction is done(he also says be aware that a correction can have greater affect when exciseing) so the correction might not apply if you allready have insulin on board from your last meal.


Sometimes even a a walk around a shop can drop a significant amount

 

[The_Bowlii]

I've pulled this post out of the thread I originally posted in as it was suggested it might benefit people by being more visible.

I read a fair number of threads with people saying that one should not exercise when high as it's not good for you (or words to that effect). I understand that DAPHNE courses may also be discouraging people from exercising while high.

As far as I understand the only issue with exercise while high is that it may increase your BG (any exercise may increase BG, depending on the intensity of the exercise) and if you're high you may also have ketones (which are not caused by being high, but are a side effect of too little insulin, which also makes you go high), you may therefore generate more ketones and potentially suffer from ketoacidosis.

I do feel this is perhaps blown out of all proportion though, especially as most people will have some basal insulin floating around.

If anyone has any links to any papers/guidance that indicates that there are other issues with exercise while high, please post, and I'll think about changing my opinion! 🙂

Edit/addition: For clarity, while (typically high intensity/anaerobic) exercise can increase BG initially, afaiu it depends on how the liver reacts to the level of exercise i.e. how much stored glycogen it converts to glucose to "help" you on the way, eventually the increase stops and BG will decrease (you run out of stored glycogen after an hour+ or more likely your adrenal response subsides more quickly than this as you become used to the activity - these are my supposition though based on experience rather than research). So basically it's not all bad even if BG does start to rise with exercise, and it doesn't always happen: if you are used to the exercise or exercise at a lower intensity.

I have no qualms about exercising when high, though I tend to ensure I have at least a little bit of (bolus) insulin on board if I'm properly high or heading upwards (like 15mmol/l+). A steady 10 mmol/l & exercise will probably drop me through the floor so no insulin required (aside from my basal, which is already there). I would certainly be more than happy to exercise with a blood glucose of >15mmol/l, though I would certainly be trying to work out why I'm high as well as fixing the problem - not taking enough bolus to cover DP before exercise often gets me, or it could be mistiming insulin/meal or misjudging carb content. Obviously care should be taken if you have a full meal's worth of IoB (e.g. if you weren't planning to exercise), as exercise will make it very potent, the same is true of taking a full correction dose and then doing exercise.

In the "Exercise management in type 1 diabetes: a consensus statement" published in the Lancet (the paper is free to access: https://pubmed.ncbi.nlm.nih.gov/28126459/ or doi: 10.1016/S2213-8587(17)30014-1) they say that levels between 10.1 and 15mmol/l are fine, though that blood glucose may rise; for levels above 15 mmol/l they say that ketones should be monitored if the high blood sugar is not due to recent food. If ketones are normal then they say to continue to monitor; if ketones are slight elevated, only do short duration low intensity exercise; if ketones are high treat with insulin and don't exercise.

Here is the actual text:

Blood glucose concentrations before exercise commencement and recommended glucose management strategies
The carbohydrate intakes shown here aim to stabilise glycaemia at the start of exercise. Blood glucose at the start of exercise must also be viewed within a wider context. Factors to consider include directional trends in glucose and insulin concentrations, patient safety, and individual patient preferences based on experience. Carbohydrate intake will need to be higher if circulating insulin concentrations are high at the onset of exercise.
Starting glycaemia below target (<5 mmol/L; <90 mg/dL)

• •
  Ingest 10–20 g of glucose before starting exercise.
• •
  Delay exercise until blood glucose is more than 5 mmol/L (>90 mg/dL) and monitor closely for hypoglycaemia.

Starting glycaemia near target (5–6·9 mmol/L; 90–124 mg/dL)

• •
  Ingest 10 g of glucose before starting aerobic exercise.
• •
  Anaerobic exercise and high intensity interval training sessions can be started.

Starting glycaemia at target levels (7–10 mmol/L; 126–180 mg/dL)

• •
  Aerobic exercise can be started.
• •
  Anaerobic exercise and high intensity interval training sessions can be started, but glucose concentrations could rise.

Starting glycaemia slightly above target (10·1–15·0 mmol/L; 182–270 mg/dL)

• •
  Aerobic exercise can be started.
• •
  Anaerobic exercise can be started, but glucose concentrations could rise.

Starting glycaemia above target (>15 mmol/L; >270 mg/dL)

• •
  If the hyperglycaemia is unexplained (not associated with a recent meal), check blood ketones. If blood ketones are modestly elevated (up to 1·4 mmol/L), exercise should be restricted to a light intensity for only a brief duration (0 min) and a small corrective insulin dose might be needed before starting exercise. If blood ketones are elevated (≥1·5 mmol/L), exercise is contraindicated and glucose management should be initiated rapidly as per the advice of the health-care professional team.
• •
  Mild to moderate aerobic exercise can be started if blood ketones are low (<0·6 mmol/L) or the urine ketone dipstick is less than 2+ (or <4·0 mmol/L). Blood glucose concentrations should be monitored during exercise to help detect whether glucose concentrations increase further. Intense exercise should be initiated only with caution as it could promote further hyperglycaemia.

Great post @SimonP. There are so many variables and limits and rules that it can all be quite overwhelming.

Good to hear that people on this thread don’t worry about levels up to 15 mmol/l which is a relief. I sometimes find myself around 12-13 mmol/l and start to panic about what to do. I often find myself walking round the village at 11pm in an effort to bring levels back down under 10mmol/l. I’ll worry no longer!

On exercise, I find I can jump up after having stopped to levels around 13 and then they come back down just as quickly. Conversely, they sometimes head down rapidly, I get the low level alarm, I correct with dextrose tabs or jelly babies and then overshoot. Learning to take my time and always do a finger prick test to be sure because Libre2 isn’t infallible.

I learned this weekend that 1 unit of insulin to 40g carbs works for me at breakfast before a long bike ride. I tried stopping for lunch with no insulin but went high (for me, 14 mmol/l) so took a unit and it all corrected. Every day is a learning day…