Carb Burn Rate?

Any experience measuring the rate carbs are burnt when exercising? I used a CGM for the first time in a couple years a couple weeks ago and found that I went through about 240 carbs in about 5 hours but that my sugars were still moving downward - seems like far more carbs than I would have thought might be needed but wondering if others had any experience. Any reccommendations for anything to eat that will keep raising the sugars over long period of time?

they say the avg is approx. 60-90 per hour..if you were doing something like sking, that is highly likely you were closer to the 90 side.. try one of the nutrition bars like Extend Bar..this bar has a slow rising sugar..but you might also try to turn down your pump to maybe a 50-75% basal..and see if that helps

It is all about the level of intensity. As an example, I exercise about 5-6 days a week, but over Christmas I did some back country skiing where we skinned up a very steep mountain--I was using my hourly exercise burn rate, but that was way off due to the level of intensity and burnt through all the glucose tabs I brought. Here is a table from a book I highly recommend: How to Think Like a Pancreas that provides some guidance based on your weight and level of intensity in terms of carbs burnt per hour.

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I usually try to have my BG pretty stable, with IOB cleaned out and have about 8-15G of carbs for 3 miles of running, every 1/2 hour or so.

After work, if I'm running 3 miles, if I'm around 90, I'll have a glass of skim milk, toss my clothes on while it's starting to cook and often get a "predicted high" alert on my CGM as I start out. 25 minutes later, on a good day, I'll get the "predicted low" alert as I get home. This has been pretty reliable for me for a while, since I got the Medtronic 523 last spring.

If you are x-country skiing, I suspect that you're exercising a lot harder though!

I’ve found that if I’m let’s say 110 before I head to the gym, I’ll eat 15g and do 1/3 the dose of insulin (0.5U), travel to the gym, disconnect my animas pump and do about a half an hour abs class, running or swimming. Since I don’t like having my pump on me, my nurse said it was important to have some insulin on board. My next goal is to figure out what to do for a longer workout.

This is a great topic. I don't have a CGMS though. My doc thinks it would be significantly inaccurate for me in particular (if someone could explain why someone's interstitial fluid would be more variable than others, I would be very grateful). I do however check my bg very often (between 6-10 times a day depending on how I'm feeling) and have noticed very odd trends when physically engaged that tend be somewhat consistent.

The short answer is it all depends. Some activities require more carbs and others require insulin.

Long answer...Okay, so I do a variety of physical activities and have a wild variance in all of them, thus the amount of carbs that I tend to eat before hand also varies alot. The primary activities that I do are: 1. Rock Climb 2. Hike 3. Run

Running: If I'm jogging/fast walking at a very slow speed (like 15min/mile), my blood sugar will drop pretty significantly, about 150mg/dl per 60 minutes. So, if this is the scenario, I eat a couple of granola bars or a peanut butter sandwich. Peanut butter tends to keep it somewhat stable. Now, if I'm running harder, like (8-10min/mile) then oddly my sugar goes up, like 100mg/dl per 30 min.

Hiking: If I'm carrying a big pack, and the terrain is steep, then it goes up at about the same rate at running; if light pack and level terrain, then it goes down at about the same rate walking.

Climbing is in a whole other category though. If the route is balancy and less than vertical, it typically goes down just a bit or stays the same so I don't need any carbs. If the route is overhung and pumpy, then it typically goes up pretty rapidly; somewhere in the neck of the woods of 75 mg/dl per climb or about 20 minutes. On top of this is fear of falling. If it's overhung, and I'm sketched about a fall, then my blood sugar goes through the roof at a rate somewhere in the range of 125mg/dl per climb. There was a particular climb at the Red River Gorge called Iniquity that shot my blood sugar up from 212 to 546 in less than 30 min. It was long, severely overhung, and super pumpy and there was a 45 ft possible fall. I took the fall which was very stressful, so cortizol levels were helping with the high bg. I hadn't eaten since breakfast roughly 6 hours prior. So fear mixed with anaerobic activity is a recipe for hyperglycemia.

I'd love to hear more stories and see more numbers for this, particularly with anaerobic exercise, as trying to configure blood sugars with all these variables is really hard!!

Sounds pretty similar to me burning over 200 carbs in that kind of time frame but I do turn down my basal to about 10-15% normal amounts, but basal experimentation is a very personal thing and I think we are all pretty different in that.

To keep level I try and always go for good old classic porridge of muesli (but only going 50-60% of the normal dose for it) so it's a nice slow burner before a long run. But keeping levels as flat as possible with sipping my way through a couple of drinks bottles of energy drink.

I am a fan of the SIS Go drink which can mixed up. In the past had been trying the usual off the shelf stuff like Lucozade and Gatorade but they just aren't anywhere near as potent enough when it comes to keeping me going...also to carry enough would be an immense burden. The SIS stuff is a mix, so I get more control over how much kick it has, but the normal mixture is about twice that of Gatorade, and the added electrolyte is handy for cramp prevention etc.

Throwing in the odd banana is usually handy also, and the off Cliff bar and things like that which take a little while to burn through.

CGM wise is handy, but I find only of use to show direction of BG. Still try and get a few finger tests thrown in when I can (usually banana stops). Seems to change quiet a bit since the CGM is monitoring the glucose in your interstitial tissue. Tend to find I get a bit high before an event due to the lower dose for the porridge and can get into the 10's (180ish in US values), until things get moving and I start to burn things off for the next hour or so (found the CGM usually going crazy at this point registering highs). A sprint or a slog of a climb can also raise my BG as I believe it's the liver playing it's usual fun and games and dumping glucose from the tissue the CGM is reading into our blood again, this can show as lows on the CGM for me, which being pretty ok on blood tests. Although that's not always the case, as the more time I find I'm slogging in the miles the more the glucose in the interstitial tissue is being depleted even with the drinks. So again good old finger tests are good to see when it is an actual low spell.

*NOT RECOMMENDED* I have been known (and yes I know I am nuts for even trying this so highly don't recommend it) to see my BG in 3's (60 in US) and being out of fuel, but knowing the interstitial glucose is there so just flogging it for a few miles to get the liver to dump it back into my bloods. Ok, it means that needs replacing afterwards, but you are closer to somewhere to get something by then...but have got that wrong in the past!

Awesome info I do appreciate the detailed feedback. I'm in agreement with the CGM giving the direction sugars change but not accuracy of the true blood sugars.
I went to the endo recently and they suggested I take "Clif Bar Builders" before going out for a full day. I've tried them couple times and it doesn't reduce the quantity of carbs needed but has about 45 carbs and 20g protein in a smaller volume than a normal meal and ends up spreading out the carbs throughout 4-5 hours. I've got a similar medley of activities and continue to try and find some in-depth correlation as it seems others have been. My main activities are 1. Back country skiing 2. Hiking 3. Running/gym 4. Mountain biking
1. Similar to Phishery's observation I have a hard time putting back enough carbs to keep a balance when skinning up a mountain for a full day, but I’ll put a +/-2hr trip in and don’t even need to eat breakfast. If I am going out for a full day I take in about 40 carbs per hour of predicted time without any bolus insulin, which usually ends up with 240-300 carbs and not a drop of insulin. I try and balance long term and fast acting carbs with a well rounded feast of a meal. While touring up I will put back another 15carbs/hour gradually and another 40-50 carbs about 4 hours into the day. Even that keeps me at a gradual decline but usually only dropping 40-60 mg/dL over a full day. If doing just an out-and back, once I turn around to start riding downhill I will usually get anouther steeper drop in sugars, not sure about the numbers on that. Once I get home I will usually have a quick drop in sugars that is easily controllable with a glass of OJ, but quickly rises too high if I take in too many carbs without a bolus. I’m about 5’9” and 160lb if that is of any value putting carb ratios or other numbers into perspective.

2. With just a day back pack I’ll have about 60 carbs with breakfast, no bolus, and take 10-15 carbs/hr without a bolus and be fine and stay in balance. Just like everything else I will have a gradual decline in sugars. If I have a +/-40 pound pack everything pretty much doubles.
3. 95% of my running is at a gym midweek after work. If my sugars are balanced across the afternoon ill have either a granola bar, piece of fruit, or some crackers before leaving work with no insulin and stay balanced through any cardio. I find that if I have a spike in my sugars that afternoon that my sugars continue to drop and am done after 30 min or when my sugars drop below 60ish. If my sugars drop I don’t usually do anything more for the day.
4. If I am doing an out-and-back on a bike starting uphill, the uphill carb burn pattern is similar to that of the uphill part skiing in that I'll put back a good amount of carbs before leaving and have a gradual decline. Many times I’ll have to stop at the top of an out and back or just after a long climb, to take in some carbs, usually 40ish carbs by means of a couple granola bars. But once I get home or just back to the car ill either be dropping or be in the high 200s/low300s, depends on the direction my sugars were moving before I started exercising. I'll try this out with a sensor come spring time.
I have experienced similar patterns to the Red River Gorge (that place looks awesome) where spikes will happen when transitioning from the consistent cardio portion to the downhill part of activities I have no answer as to how to predict or prevent it.
Going another layer deeper, I sit at a desk job during the week, I have found that after a few rigorous days on a weekend, I sit in a desk and carbs don't react in my body immediately and eating just a banana the carbs reacting in my blood will be spread out over time while taking a normal insulin dose drops my sugar immediately.
Greatly appreciate the insight I've received from all.