Exercise + Insulin = SUPERINSULIN!

While insulin on its own barely does anything at all!
Although every day is a bit different.
I had my usual 40 g carb breakfast today 20 minutes after bolus (4 units) and went to work, watching Dexcom climb and climb and climb over from a start of 5.9, up to 8, 10, 12, 14… then I decided to go down the stairs (5 flights) and back up again. Within 20 minutes, Dexcom shows it’s back below 10 and not long afterwards down-arrowing to 5.5. Needing an emergency butter tart.

Don’t worry: tomorrow will be something different.


I agree – insulin is super-charged when combined with exercise. Mornings are tough for glucose control since we also need to overcome circadian counter-regulatory hormones like cortisol and growth hormone that interfere with insulin’s normal action.

Have you ever considered skipping or delaying your breakfast meal? That way you can sidestep the morning drama of the war between insulin and its natural metabolic adversaries. Although you were able to manage to bring down your glucose level with some simple exercise, you still suffered a steep climb and descent including a hypo. That glucose volatility is not normal and your body does not like it.

Why not experiment one morning and skip your usual breakfast? Many people, including me for many years, just ate breakfast out of habit. I usually did not have an appetite but reasoned that my body needed it. I think one’s body can make its needs known readily by releasing a hormone that drives appetite.

Sorry to answer questions you did not ask!


I exercise with every meal.
I eat a very small breakfast usually a banana and coffee.
But I walk a mile to eat lunch and a mile back.
I walk 1.5 miles after dinner to get coffee and back.

Yes I really love coffee.
If I don’t do just that much walking, I’ll need twice as much insulin.


I’m with Timothy.

Usually I’m fine with these amounts during the week but then I have problems on weekends when more active. I keep having to snack to avoid crashing!

It seems that I am sensitive to:
1: Carbs
2: Insulin (except when I’m not!)
3: Exercise.

What can I say? I’m a sensitive guy. :grinning:

In Line with Terry 4: in the short term, I do best on low basal and skipping meals entirely. Unfortunately I end up out of whack later when I skip meals. Sometimes highs that take 10-15 units or more to correct! So I try to have 3 meals a day.

I just wish thing were more predictable and consistent. Although I’m my own worst enemy: weekend warrior, habit eater (let’s not talk about my six hour adventure into the 20s after popcorn on Friday night).

My glucose level in the morning is almost always between about 75 and 100. My glucose levels don’t rise much when I get up, but if my glucose level is over 90 I inject my 3 units of Novolog right away. If lower I wait until right before I eat which is about 10 minutes later.

My breakfast always includes 1/3 cup of cooked oatmeal, 1 cup of blueberries, 1/2 of a banana, a date and a cup of coffee. I keep an eye on my meter and when I reach around 110 to 130 I ride my exercise bike for 1/2 hr. By that time I am back to about 80 to 90.

I am retired, so I can do what I want when I want. I almost never skip meals, because I enjoy sitting down and taking a break with my husband. I usually ride after lunch also, but seldom after dinner.

If I didn’t ride the bike about an hr a day, I would have to give myself more insulin. I think insulin and exercise go great together.
I am mostly a low fat vegan. Type 1 dx in 1959.


This has long been true, and when I’ve mentioned it to my endo, they never really responded with their thoughts. I would wonder if it was increased insulin sensitivity or a revved-up metabolism and have recently seen reports of an optimal time for exercise to improve metabolic health, late afternoon or early evening.

I work out aerobically on most days - a recent shoulder injury prevents lifting - during the week around 7, but on weekends late afternoon. Regardless, I need to increase my basal insulin on days I do not work out to compensate, and on days where I have both long intense walks and separately exercise, have more issues with lows using my normal short-term doses.

Separately, now that I work exclusively from home - pre-pandemic it was a hybrid 3 days in, 2 days out - I have more issues with my insulin being completely ineffective unless I take a walk after injecting. When I was in the office, I had an intense 15-minute walk to work, as well as going home, and went out to lunch to a local salad eatery, and each of these efforts helped my insulin to kick in.

Fully agree that exercise makes short-acting insulin KICK IN.

But I also find that if I’ve been inactive for a while the CGM lag seems to grow. Then when I get up and move, that it suddenly catches up. Just because it appears sudden on the CGM display, I think in some cases that bg was already dropping, but because of interstitial fluid lag that the CGM wasn’t showing it yet.

So why you ask? Insulin seems to work faster and more efficient during activity because the insulin receptors, the the insulin uses to open the cells to take in glucose, multiply on the cell wall in response to activity and the demand for more energy. This happens almost immediately when you start a physical activity…like in nanoseconds.

However, this can only happen if there is enough insulin and no counteracting actions or components to the insulin action, like hormones, drugs, or strenuous muscle action.

It pretty amazing that the body is so responsive to activity and why insulin works better with regular activity. Even after 51 yrs w/o my own insulin I’m still amazed at what the body can do if I help it.


The biggest challenge is when I overdo it and it goes down down down and I’m sucking back the juice boxes. . . Like right now.

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You might need to alter the insulin you take. I take different amounts weather or not I’m exercising.
I average 6 units for a meal, but sometimes as low as 4 or as high as 8 depending on my activity.

I’m on a pump so my basal rates change as needed. It’s harder to regulate that when you inject long acting insulin, but it’s still possible if you split the dose.

AKA “Rage Exercise” to extend the concept of “Rage Bolus” :slight_smile:

The IOB (insulin on board) concept in pump computations has some value BUT it would be even better if there were a factor behind ISF to account for increased sensitivity or more rapid absorption. (Or both, more rapid absorption actually decreases IOB in subsequent hours).

I hadn’t thought of it that way but you are right.
10-15 minutes on an exercise bike, less on the Nordic track ski trainer, a bit longer on the treadmill (all three machines are set up in our TV room) will affect me more than 5 units of Humalog!!

Exactly! Exercise almost always gets insulin absorbed and in the bloodstream faster and regular exercise lowers insulin resistance. The only time exercise doesn’t help is if you’re in diabetic keto acidosis or for some people strength training makes their bg go up.

One other thing about exercise: it continues its benefits for a longer time than most people realize. If I do my usual morning and afternoon walk, and especially if I do some stretching and muscle-building exercise, my BG seems to flatten out for a couple days thereafter. So if I do it every day (which I pretty much do), I’m good permanently. I do have to be sure my BG is sufficiently high before I exercise, but that’s second nature by now (61 years as Type 1).

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What are these numbers’ units, that you posted? I’m not familiar with them. But intense exercise does bring down the glucose level fast. Something about anaerobic exercise causes very rapid change. I find, too, that the more fat I have in my meal, there will be a second peak and it will take longer exercise period to pull it down. It usually hits some 2-3 hours after eating, so you can program it into the pump, if you have one. Someone said to input about half to two-thirds the amount of carbs as the fat calories would indicate. So, 3 grams of fat is 27 calories, and divided by 4 to get equivalent carbs in grams, or 7 grams, then multiply that by 2/3 to get the number you input to the pump for a 3 hour bolus.
I keep asking Tandem to add a feature to let us program a time-delayed start. The last time, the person was a diabetic on pump and she said she is going to submit that with emphasis. This would help tremendously to better manage the fat portion of our calories.

The world is divided on the denomination of blood glucose units. Most countries use mmol/L (millimols per liter), while others use mg/dL (milligrams per deciliter). Canada uses mmol/L and the US chose mg/dL as its standard.

Seems universal human agreement on anything these days is a fantasy.

Conversion between these two systems is easy. Take mmol/L and multiply by 18 to get mg/dL. To go the other way, just divide by 18.

3 mmol/L = 54 mg/dL
4 mmol/L = 72 mg/dL
6 mmol/L = 108 mg/dL
8 mmol/L = 144 mg/dL
10 mmol/L = 180 mg/dL


Ha, you sound a lot like me.
Just got a Dexcom last week. I used to only exercise (vigorous 50 min workout) BEFORE breakfast (but SO hungry!) because it was so impossible to take the right insulin, eat, drive kid to school, then exercise in the morning - I’d always go low during, or high beforehand.

So recently I decided I’d just do a little exercise a few times a day, after a meal and as I started to rise.

What do I do?! I work from home so 20-30 min after a meal, if i’m rising (220/12mmol and rising) I put on my teen’s VR headset (she’s at school, after all) and do a dancey/sword-fighting “Beat Sabre” workout for 15 minutes! Ha! And back to normal.

And worst case scenario, there’s always butter tarts to help if I over do it. :wink:


Perfect example. I had lunch around 1315, bolused for 45 g of carbs, returned to work, and noticed it climbing for the next 45 minutes. Brief walk for 5 minutes sent it in the right direction so I went back to work until it started climbing again! So I did a more strenuous exercise for about 20 minutes — and fixed it!


Oh, man! I remember when I started using my Dexcom cgm and the wealth of info it gave me regarding exercise.

For the first couple of days after I started on the cgm, if I saw a rise in glucose levels, I would kind of panic and go for a walk (about 1 mile or so). Glucose would drop…and drop…and drop. I learned to pay more attention to 1) how much insulin was on board from my pump, and if there was any, to either be patient and watch for glucose levels to come back down, or take a shorter walk; 2) drink a glass of water–sometimes dehydration plays a role in how your insulin circulates in your body.

If my glucose readings are around the 100 mark and I’m going to exercise, I usually either turn my pump basal down for 1/2 hour or eat some protein. I prefer to exercise at around 120-130 if I’m walking. If I’m lifting weights, I don’t turn my pump down, but I watch the cgm closely because lifting weights might push my glucose levels up.

It takes a lot of planning! It also took me a while to figure all of this out, but If I could do it, you can, too!

Thanks, Terry.


Eternal vigilance is the price of liberty - power is ever stealing from the many to the few. - Wendell Phillips

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