At first cycling used to make my blood sugar go down, but now

I was diagnosed with type 1 diabetes in April of this year at the age of 43.

My whole life Iv'e been into long distance running and bicycling, well I did have to give up running due to a calf injury which became too bad to run last year so now days I ride my bike, do sit ups and push ups.

After being diagnosed with diabetes I didn't think I was going to be able to ride like I used to because back in April diabetes made me lose about 30 pounds. I went from 175 down to 145 very fast. I have gained 10 pounds back since then so I'm 155 now and riding like I used to like 10 years ago and still improving especially on the mountain climbs. 

Back in late may I decided to do the Tour de Cure which raises money for the American Diabetes Association. When I started my training I noticed that when I would ride my blood sugar would go down and sometimes it would go way too low so I started eating a powerBar that had 30 grams of carbs. I'd check my blood sugar around 20 miles into the ride and would take it every 20 miles after that. Each time my blood sugar would go down and I'd eat another powerBar. Generally my blood sugar would be around 90-160 before, during and after the ride. Lately my blood sugars have been going high during and after my ride so I would only eat about half a powerBar, but still my sugars are still going very high so the last 3 rides I've gone on I haven't been eating anything before my ride and my sugars are still going up. However, about 2 hours after the rides my blood sugar has been dropping. Lately what's been going on is my blood sugar has been about 160 before the ride, then going over 200 20 to 30 miles into the ride and 180 after the ride and that's without eating anything for half of a powerBar or Cliff bar during the ride.

This weird blood sugar stuff actually started at the Tour de Cure last Saturday August 20th. Before the ride my blood sugar was at 150. I ate a 30 carb PowerBar. Took blood sugar about 30 miles into the ride and my blood sugar was at 300. I asked a person at the medical tent at the aid station what to do and she suggested I take 2 units of insulin and wait about 20 minutes to see if it starts going down. I went down to 250 so I rode another 30 miles and it went down to 220 and after the 100 mile ride my sugar was at 200 and I only had the powerBar before the ride and only a half powerBar during the ride. Hours later it finally did drop to a good level of 120.  

It seems like the better shape I get into the higher my blood sugar goes. Has this happened to anybody else?

When you exercise your muscles release stored glucose called glycogen.  Your blood sugar drops because your muscles take glucose from your blood stream to replace their glycogen stores.

Over time of doing the same phycial activity, your body gets more efficient and does't need as much glycogen to get the job done.  So that's why you're not noticing the blood sugar drop like you used to.  Exercise is still good for your blood sugar because it makes you more sensitive to insulin.  

There's a great book by type 1 diabetic and exercise physiologist Dr. Sheri Colber called "The Diabetic Athlete."  It outlines how to adjust food and insulin to accomodate the effect of different sports.  I'm also a fan of Gary Scheiner's Type 1 online classes, including the one on blood sugar control and exercise.  He's a longtime type 1, exercise physiologist, and author of "Think Like a Pancreas."  The online classes are $30 and he'll answer your specific questions as he does the online presentation.

Thanks Jenna,

I definitely need to take classes. I think I also need a new endocrinologist as well. Whenever I talk to her about all this stuff she just tells me to eat less. So I try eating less and I'm hungry all the time even 10 minutes after I eat. I tell her I workout hard pretty much every day, I'm 6 foot and 153 lbs and I've lost 2 more pounds this week and I've only been having like 60 grams of carbs each meal but my blood sugar has been going up. I've also been injecting more insulin than my endo has been telling me to inject. I've also been thinking about a constant glucose meter and an insulin pump but my endo seems to be anti pump. Guess I need to find myself another endo.

Hey Brian, I've read the Diabetic Athlete and I recommend it as well. I was a long distance runner before being diagnosed with type 1, so I was frustrated with how hard it was to figure out managing exercise with blood sugar as well. Generally, you're going to need to eat carbs before you go and then depending on how long you're riding, you will need to take in carbs as well. The way that I think of it (and the way a good nutritionist explained it) is that we have to take in the same amount of carbs that we're burning -- non-diabetic people burn the same carbs, but they're body can adapt and regulate and mobilize carbs from other places. We still end up burning calories, overall, but we have to regulate the fast energy.

That said, there are also factors that can cause your blood sugar to rise, instead of fall. Like Jenna said, when your body becomes accustomed to one level of exercise, it takes less energy to do it. So you may not need as much sugar to cover it. Additionally, your body may need more insulin to help deliver the fuel. So you may consider raising your basal. Finally, anything to increases stress (cortisol) will result in the liver releasing blood sugar and therefore a raise in BG. So, if you're pushing it really hard up a hill, you may get a raise in BG.

It can get complicated...

Do you live in NYC? I have a friend who's a very fast runner who was diagnosed at 37. I can put you in touch if you're looking for someone "demographically" similar to yourself. But I'm happy to answer any questions.

In addition, I'm on the young leadership committee (YLC) for the NYC chapter of JDRF. We're trying to figure out ways to use Juvenation and raise awareness for both Juvenation and YLC. One feature that I'd like to work on would be better resources for athletes. It sounds like you'd be interested in something like that and I'd really appreciate your thoughts. Feel free to email me at !!

It's a tough diagnosis, but you'll figure it out -- and make friends along the way.


Yes, I guess I will start having a little insulin before I ride and eat a whole powerBar and after a few hours of riding see where my blood sugar goes. I've just been kind of afraid of having Humilog Insulin in my system with exercise but it looks like that's what I'll have to do, but I'll just take a couple of units I won't take a whole dose.

And no, I live in Littleton, CO right at the base of the foothills so everyday I ride I have big hills to climb. We did just move to this location from the east part of the Denver area which is a lot less hilly so the rides were much easier out there, but out here there's hills on the hills LOL!!

Thanks for the info. It's nice to have some people to talk to on this board about stuff like this. I'm just such a newby to this diabetes craziness.  

Do you take lantus? I think it might be better to increase your lantus by a unit or two -- I can't take fast acting (novolog or humolog) within a few hours of working out, no matter how many carbs I take in before.

But one unit or a half unit of fast acting might help -- every person is different and of course it depends what you're doing!

ALSO definitely buy a box of GU. I eat 15g of carbs before I head out the door and if I'm going to run for over an hour, then I start eating half a gu (about 10g) at 40 minutes and take half every 20 minutes thereafter...

You definitely should consider seeing a new endo.  I'd really recommend the Adult Clinic of the Barbara Davis Center for Childhood Diabetes in Denver.  I haven't lived in Colorado for years, but went to Barbara Davis as a kid and young adult.  They are extremely knowledgable, personable, and are savvy about treating diabetes in real life.

Exercise is the toughest variable in managing diabetes.  I'd had type 1 for 25 years and was clueless about dealing with exercise until I read Sheri Colberg's book.

Because you're cycling more hills now, there's a good chance your muscles are dumping lots of glycogen.  This is most common in anaerobic sports like weight training, but bicycling has done it to me before.  In that situation your blood sugar goes up after exercise, but you might notice an unexpected low 10-15 hours later.  

I grew up in Ft. Collins, CO but went to college in Durango, where there are serious hills.  First couple of weeks my glucose was lowered by the cyclling, but then I noticed that my blood sugar would actually go high!  It felt wrong to take insulin, but I ended up experimenting and taking a small dose.  Whether you add insulin or not, test a lot and be sure to have food with you on your rides.  

Thanks everybody for your suggestions. So what I've found what works for me is to eat about 20 to 30 carbs before I ride and take 2 units of Humilog and about every 30 miles or so eat another 20 to 30 and my blood sugar drops to 120 to 150. I never thought I'd need humilog when I ride but it works.

Now I just need to stop hitting 200 or above before I go to bed. I think it's time for a continuous  glucose meter and an insulin pump. I'm just kind of sick of injecting insulin 5 to 8 times a day.

I tried that and it did not lower my bs very much but thank you so much.