How fast does your sugar drop?

Im just curious because I know for me, if i start any exercise below 200-250, Ill be low in 10 minutes. For me, 30 minutes of exercise drops me 150…so i know how to calculate how high i should be, and that is just for walking! cycling drops me 150 in 15 minutes.

the worse part? I also disconnect from my pump and i still drop that fast!

how fast do you drop?

Are you exercising while your bolus is still active? I exercise 4 - 5 hours after my last bolus (shortly before my next meal) so that the only active insulin is my basal. If I don’t do anything extra (I’ll explain in a bit) my glucose will drop about 60 in a 30 minute jog. It would keep dropping afterwards for a while if I didn’t eat anything.

I generally start a run at about 110 - 120 and end at about 90 - 100. About 90 minute before I exercise, I drop my basal to 50% for 1 hour. Then 30 minutes before I exercise (assuming my glucose is in the 100 - 120 range) I consume about 10 carbs (e.g. juice, fruit). That way just as I start my exercise the carbs are really kicking in and starting to raise my glucose. At the end of my run, I’ll consume another 10 carbs and then usually eat within the hour. If my glucose is over 150 at the 30-minute before exercise period, I skip the 10 carbs.

I wear a CGM and I can see my glucose going up a little at the start of the run (e.g. from 120 to 140 or 150) and then start down in the middle of the run. By the end of the run it’s back to almost perfect. Not every run is perfect, but I can do this pretty consistently.

Exercising in the 100 - 150 range feels so much better than starting out over 200 (which I used to do when I was on MDI).

yeah according to my pump there is no insulin on board before i disconnect. I just dont know why i drop so fast and its such a drastic drop too. Is there a difference in the rate that i drop depending on how much muscle mass i have vs. fat mass?

I wonder if your basal levels are too high. Have you ever done any fasting basal testing?

Basically, here are the steps:

  1. Eat modest low-fat meal and bolus normally to cover the carbs
  2. Wait 4 hours (when bolus should be about done), start testing your BG every hour
  3. If your BG is too high (>200) or too low (<90) you should correct and postpone the test for another time
  4. Keep testing every hour until your BG changes by more than 30 - 40 or until you’re starving

If your basal is correct for that time of the day, you should have a fairly flat BG. If it drops, your basal for 2 hours before the drop starts is too high. If it rises, your basal for 2 hours before the rise is too high.

Here’s a good article about setting basals Getting Down to Basals

You might also try the temp basal for an hour or two before you start exercising. Given the amount of BG fall you’re experiencing, there must be too much insulin in your system when you start exercising. It takes experimentation, so don’t give up. You can find some techniques that will work for you.

Hi Sarah, Ken is right, but you might not have to go to the trouble of basal testing (personally I hate doing basal testing so avoid it if possible). If I read correctly, you are not reducing your basal rate prior to exercising, but just disconnecting while you exercise. Try reducing your basal rate by 50% (or maybe even 75%) one to two hours BEFORE YOU START exercising and see if that helps. I reduce my by 50% for the 1 to 1.5 hours prior to starting exercise and that typically holds me steady for short workouts (45 minutes or less) without any extra carbs. Disconnecting just during the exercise won’t do anything to stop you from dropping during the workout because the basal insulin that is working during that time is what you were pumping in the last 1-4 hours (assuming you are using Novolog or Humalog). Also, if the exercise you are doing is new for you, you may drop more than once you adapt to it. I have found that to be true, but YMMV.

Well heres the thing, it depends on where my bg is…if its 100-150, ill decrease my basal to 10% for up to two hours before i go to the gym. then I disconnect. So im really not getting very much insulin and my bg is generally pretty high when i start…ranging from 250 to 380 generally. Its really weird isnt it? Sometimes, because im stubborn and am determined to finish my workout, ill even drink faygo soda…aka its really high sugar, to keep my blood sugar up…and i still end up between 80-100 when i stop. My doctors advised me to have some protein after im done and decrease my basals (once again) to 40% for the 4 hours following my workout. the next morning i wake up in the 80s. and i generally only workout for an hour to hour and a half, depending how fast i drop.

And ive been working out and swimming competitively since i was diagnosed when i was 11 and im almost 22, so exercise isnt new to me. but they did play with my basals a few weeks ago when i started my new cozmo pump

its starting to sound like my basals are too high…

Those kind of very large swings are really difficult to control. Are you fairly stable at a good level on days that you don’t exercise? If not, you should probably avoid the exercise for a bit and try to get a stable baseline first. Then start adding a little exercise at a time (maybe just a 20 minute work-out at first and slowly increasing as you see what works to keep your glucose more stable). I quit running for a while when I first went on the pump. And now I’m adding it back into my routine with very good results.

There’s a good chapter on T1 Diabetes and exercise in the book “Pumping Insulin”, by John Walsh. You might want to get a copy of that and look it over. You may be able to find a copy at your library.

One possible explanation that just came to my mind is that your body simply isn’t absorbing your insulin properly until you exercise. Then a bunch of accumulated (pooled) insulin is quickly absorbed once you get active. Where do you insert your pump catheter? Is there enough body fat there or might you be getting into muscle? You recently started a new Cozmo pump, were you pumping before or on MDI? In either case, did you have these kinds of glucose swings before when you exercised? It’s always good to look at the most recent changes as a possible cause.

Ive been pumping snce 2003. Ive always been this way and its quite frustrating. I am, sadly, overweight. I did weigh 265 and I got myself down to 200-205. This was great because my insulin levels dropped immensely. My body now has 35% fat, so im really muscular for a girl, but i still have surface fat, and where i insert it is in the fatty parts.’

the pooled insulin theory is a good theory. it does make sense. Ill most likely have to bring this up with my endo.

but until then i’ll just enjoy eating a bowl of pasta and running to the gym to bring my sugar down instead of bolusing.

Hi Sarah,

Like it was suggested by Ken, it looks like you have pooled insulin in your body. I call it “Insulin Latency”. I think I may have picked that up from somewhere like Dr. Bernstein.

I run 4 morinings a week and don’t use a pump so my advice may not be very useful for you.

I sort of have my insulin usage down to a an in-exact science. If my blood sugar is 90 when I wake up, I take my long acting Lantus, (4 units) and one unit of Humalog (This covers what’s known as the “moring effect”. I’m pretty sure you know what that is.). Then I go running within 15 minutes. When I return after about a 30 minute run, my BS is usually around the same amount, 90. If not, if it is low, I take glucose tablets to make up for any low. IMMEDIATELY!

But, if I wake up and my bs is high, I take the same Lantus, and Humalog on a sliding scale. It also depends on what food I had the night before. I never eat before going for my run. I prefer to let the “morning effect” take over for what I need for energy. It seems to be quite consistent. (Man, this is getting confusing, isn’t it?)

When I run, I find that I need less insulin for my breakfast as well. That would seem to make sense, wouldn’t it? And I tend to eat just about the same thing for breakfast every morning so I know what kind of dosage works. (Oh yeah, I tend to favor 4 eggs, scrambled, and a banana for my morning petit de jeune’.)

Any way, this works for me along with eating a low carb, paleo-type diet. Of course I’m not perfect with the diet. I tend to cheat a bit. I love cheese and crackers, prefering some sort of strong swiss cheese and red wine to go with it. But that’s me. I don’t recommend this for anyone else. Unless of course it’s your desire as well.

So, I hope this little missive gave you some idea. It really works for me and my Endo says I’m just about the healthiest Type 1 he knows. And he knows a lot of them. One more thing, my last A1C was 5.4. I may be a bit more obsessive than most with my control but it keeps the clouds out of my head.

Best of luck with your excercise routine. Keep at it. It’ll come aroudn with a littel more trial and error.


P.S. I hate to be the “bad guy” but, you really shouldn’t be eating a bowl of pasta if your diabetic. Pasta is something best left to non-diabetics who don’t over eat. Sorry for the bad tidings.

Thanks Andrew, I know about the pasta…it was intended to be a joke. lol.

I called my doc yesterday. They decreased my overnight basals by 1 whole unit, which, as many of you know, its a big deal. I have to call them back in 2 mondays.

I will say that Im not waking up in the 40s, then overeating, then correcting, then working out…it was so up and down. Hopefully this leads to better control!

HI, Sarah…I’m new onboard here, and I’ve quickly scanned the message history. We must be cut from the same cloth. My glucose drops rediculously fast when I am exercising. I hate starting out with highs, but it seemed that was the only safe way to go and even then I dropped if I went over 30 minutes. I ended up snacking thru my entire workout, which felt counter-productive, as I felt like I had a rock in my stomach. Someone in my spin class suggested eating pumpkin or a sweet potato before I work out. I can’t recall the book he referenced, but I think it’s the one that claims to cure everything without meds and that many people with diabetes don’t really need insulin…I’m not sure I buy into that, but I am trying to find some good pre-workout snack options that won’t weigh me down and help keep my blood glucose stable.

I wish I were disciplined enough to say the my schedule stays consistent where I could cut back on my basal rates at lunch, etc. But invariable when I try that route, I end up not getting to the gym and my blood sugars get higher.

Glad to have found this group and hope to learn a bunch!