Exercise and the day after lows

Hello! I’ve posted quite frequently lately and appreciate the help. If you’ve been reading my post you’ll find that I’ve been on a weight loss journey and while that’s been super successful my blood sugar hasn’t been easy to control (particularly a lot of lows) while I adjust insulin levels to make up for less body composition. I’m at a somewhat tricky point where my basal now seems to be perfect when I’m not active- My blood sugar seems to be appropriately responding to my blouses and I’m
no longer dropping in between meals. However, the day after I’m somewhat active have still been a struggle. I’m doing temp basals before during and for a little after exercise and snacks like I’m supposed to be doing but I’m just so extra sensitive that I’m usually if not low borderline low between meals which makes taking insulin a little tricky because I don’t want to drop when I wait for food to kick in (I still take insulin immediately if I’m 85 or above but if I’m let’s say 70, I usually at least wait 15 minutes to make sure I’m not dropping more). I use a pump but my doctor is very hesitant about doing a temp basal for the 24 hours after exercise. I even suggested two different basal profiles and they said that it could be a pain and hard to remember to switch between the two. I know fluctuating blood sugars are part of diabetes but I’m at the point where I’m so sick of lows I don’t know what to do. It just seems like all of the diabetes knowledge I have isn’t a match for this which is hard because I used to feel so confident in what I was doing after over a decade with it. I’m just looking for tips from other active type 1 diabetics about what they do the day after exercise if they’re also sensitive. Thanks!

Hi @Tee25. Although your doctor doesn’t want you to try different profiles, you know best what’s going on with your body and sometimes we just have to experiment to see what works. I’m assuming you’re experienced with your pump in addition to your several years with diabetes - and that you’re responsible enough to remember when to switch your settings back or set a reminder ("Hey Siri…!). If I were to suggest one thing it might be to set your temp rate for a shorter time period to start with, just to be safe. Maybe try 12 hours, see how you do, then increase a bit as necessary.


What Dorie said. We’ve seen the effects of exercise for 12 hours, easy. If you’re seeing 24, I’d believe you. Start with 12 and take it from there sounds right to me.

Taylor @Tee25 what you are observing post exercise is very common - perhaps more common than uncommon. what I suggest, is that you observe carefully how your body reacts to exercise, AND how your body responds to carbohydrates during and post activity. YES, you may need to use different insulin:carb ratios during and following exercise; easiest way is to have specialized Profiles. I, and several other Members have posted detailed responses to your question - use the search feature.

Weight and Basal Insulin: There are many published papers discussing the correlation between body fat and insulin needs. Essentially, the less body fat and body mass, the lower injected/infused insulin needed. Some doctors still calculate insulin need based in a person’s body weight - known as “sliding scale”.

Insulin pumps prescribed by knowledgable doctors for persons with diabetes ALL have to capability to program multiple Profiles / Patterns. The t-Slim Tandem pump has capability for six Profiles, each with up to twenty-four “Timed Periods”. These features are intended for use - your doctor may need to be “educated”.

There are a few insulin pumps available, at very low cost, for people with “lifestyle diabetes” who need only a constant 24/365 flow of supplemental insulin.


Also, what Dennis said. Remembering to switch to and from the “exercise” or “active” profiles you’ve programmed isn’t any different than remembering every other thing you remember as someone with T1D!

in my opinion, @Tee25 its maybe time to venture off the reservation. When my endo suggests something I don’t like, I tell her that “when she gets diabetes, then she is welcome to try that”. Now, I have an unconventional relationship with my doctors, so that may not be right for you… but you you may just want to try wielding a little power, and see if it feels good.

the right basal keeps you from rising or falling when you are not eating. that’s all. if it is set by temp or by pattern or by hard code it is just a rate.

the more exercise and the smaller you get, the less insulin you will need. this of course has a limit, and the number will never be zero, but exercise reduces my insulin requirement by 50% (FIFTY PERCENT) meaning, I have to reduce insulin, and I do so by the means that makes the most sense, and is approved… by me (typically temp basal) . cheers and good luck


Hi @jo. I like your term “venture off the reservation.” Took me a minute to get what type of reservation you were referring to but once I did I really appreciated it. I’m going to tuck if away for future use. And of course, excellent advice. We live in our bodies and can best determine what works best. Doctor’s concerns about whether patient will remember to re-set in time are valid but it’s part of taking responsibility for our own care.

@Joe and @wadawabbit Have to agree with Joe, going “off the reservation”…now and then and accompanied by good judgement and research…is a good thing. I’ve been a rule follower most of my life, but always while exercising a good deal of “judgement.” We each have our own lives and while we should listen to doctors, what we pay for them for mostly is “advice,” not authoritative decisions we have to live by. Good to discuss the facts with “trusted” advisors, but it’s each of our own decisions how we ultimately act…as long as we can deal with the consequences. That goes for exercise, dosing, and every other decision we make.

Agreed! I just tried adjusting it for the first time today. Having a hard time staying up in between meals so hopefully this will help! Had a really active weekend so not ready to say my run of the mill couch potato one is off yet.

Hi @Tee25,

T1D since 1990 here. Started with finger sticks/MDI, switched to a Medtronic pump in 1999, now using Tandem Control-IQ with Dexcom.

Discovered the same issue when I first flirted with CGM in the early 2010’s and dealt with it using temp basals and reducing meal boluses. I tuned it with the help of my Endo and a really sharp RN/diabetes educator. I found I was able to manage it manually, for the most part. What I discovered was that effects of sustained or intense exercise could last anywhere from 8-24 hours for me, most effects were in the 8-12 hour range, but if I were not able to control the initial drop, I’d of course have rebound highs that made things more difficult to control for a longer period of time.

Today, I’m still working out how best to work with Control-IQ. I often had repeated sustained lows after exercise when I initially switched over. Since Control-IQ doesn’t support temp basal rates, I’ve made some progress by starting exercise mode sooner and reducing meal bolus ratios down before and after exercise, but it still needs some tuning.

I wholeheartedly agree with the sentiments in this thread. Advice I give newly diagnosed folks I meet: This is your condition, you are the ultimate authority on what you actually do. Take in the advice of your trusted advisors/medical team and educate yourself so you can make safe, informed decisions to stay healthy and safe. Pretty basic and generic, I know, but when I was diagnosed at 25, it’s what I needed to hear.

Thanks for posting this and I’m looking forward to hearing how you do!

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