Insulin Pump--Reduction in basel rates duriing cycling?

Hello fellow cyclist! I need some help...
I always struggled to maintain my BGs on long rides (>2hours). At the time I was not wearing my pump during these rides for fear of low BGs. During my 1st Tour de Cure I noticed a lot of Red Riders were wearing pump during the event. From discussion with some of these riders I learn about using a reduced Basel rates while cycling. I was pointed to a diabetic athlete website. I since forgotten the name and can’t find thru Google searches.
Anyway, long story long…
This site had a chart for adjusting Basel rates base on time of activity and intensity level.
Does anyone know where I can find this? Thanks in advance

YOU must wear your pump!! 2 hours of no insulin will cause your bgs to sky rocket later. I cut my basal rate down to 60%. I check my bgs and I use the CGMS. I like eating cliff blocks while I ride. A non type 1 diabetic needs carbs every hour so you should too. Here is a 63 mile ride. Look at my effort. I am at 60% basal rate.

Make your pump act like a pancreas.

Sometimes I need to give myself some insulin when I am done. There is a delay. Plus cut your basal rate 45 min to a hour before you ride for the same reason.

Just to add what John said, on long road rides (longer than 25 let's say),
I use a 30% drop in basal and use the temp basal feature in Animas. Usually I know roughly how long a ride will be, and program the temp to go the duration of the ride. Even with a smaller basal, definitely take in carbs every hour. I agree with John as well, start your lowered basal about an hour before the ride as there is a delay. I also try to start a ride at a decent sugar level, around 120-150, to anticipate a drop later on.
This works great for road rides - if you are doing big hills/long climbs or with a really fast group (20-21 mph pace), you may have to drop basal or increase carbs a bit more.
The same applies to intense mountain biking with sustained long climbs.
Also, watch for after effects of low blood sugars several hours after an intense ride, I have had numerous times where I had to back off on insulin to carb ratios and correction factors due to the after effects of exercise.

Good luck,


Thanks John for you insite. Impressive ride! Almost average 20 for 63 miles, I just did a 65 mile tour de cure at 16 mph...Iwas prety hilly though.
If you dont mind I have a few ?s on the CGMS
Does your healthcare for it?
How much flutuation do you see on a ride taht you posted?
Thanks again, Ed

Hi Ed,

I find the really helpful but I am not sure if there is a chart on there. I find that it depends on the type of cycling/number of hills but I usually reduce my basal rate to 30-40% starting from about half an hour before cycling. I then change it back as soon as I stop so I don't go high (then drop it back to 80 or 90% overnight to stop me going low). I even do this for my commute which is only 45 mins but it means that I don't need to worry.

I would only take my pump off for a 45 minute gym class or swimming. Anything longer and I would always keep it on, even if only at 20%, then there is always some insulin going into you.

the other thing I do is stop roughly every hour, do a blood test and eat 20-30g carbohydrate. The stopping also means that you can change the basal rate if needed, although it is not a big enough change to notice a difference in a short amount of time.

I hope this is helpful. I know everyone is different so the rates and timings are probably just my experience.


I primarily mountain bike and usually set a -40 to -60% basal on my pump when I'm arriving at the trailhead to go for a ride. My rides tend to be 14-30 miles over 1.5-2.5 hrs depending on the terrain, time allowed and who I'm riding with. I'll usually eat a cliff bar on the way to the ride with no bolus and something with a faster acting carb profile like fruit or a gel prior to starting to keep my sugar level until the cliff bar carbs kick in. No additional during ride carbs are usually taken. Have had good success with this so far, sugars seem to stay in target range, I don't have a CGM.

Post exercise boluses were mentioned above, I too have found I can generally get away with cutting my bolus amounts 35-50% after a higher intensity ride for post ride carbs without going high.

I am lucky Medical Mutual picks up my CGMS. At first it was a battle.

I have an exercise basel program that gives me 0.25 units per hour then I switch back to my normal basel when I am done with the ride. I take Heed and GU during the ride and raisins and skittles if I go to low. Plus water its in the 100's here.