Wednesday, May 7, 2008

Pre-Workout Basal Rates

Over the past month and a half a smaller percentage of my workouts have been cut short by exercise induced lows than the percentage of workouts cut short in my previous 10 months of training. In addition to using PBN's Ironman Cocktail and EFS I've experimented with my basal rates. This experimentation has led to much more stable blood sugars during exercise.

Under the advice of my previous endocrinologist I was reducing my basal rate to 5% or 10% of the hourly delivery 90 to 120 minutes prior to exercise. This effectively reduced the novolog in my body to zero, meaning I was exercising with no insulin in my system. After reading a few articles on sports medicine and nutrition it occurred to me that insulin was necessary to help move carbohydrates from your stomach and blood stream to your muscles. Without insulin the carbs I was ingesting sat in my digestive track and were not transferred to the body parts that required energy. I think this is why when I'd return my pump to normal settings after an exercise low my blood sugar would sky rocket.

After 6 weeks of experimentation I have settled on turning my pump down to 30% of an hour's full basal rate and maintain that delivery rate of insulin for the duration of exercise (except swimming when my pump is detached). This change has allowed me to maintain a blood sugar of 150 to 190 during exercise while more importantly transferring energy to my muscles. Granted my fitness improves weekly but over the past 6 weeks I have not had the fatigue, cramping or bonking issues I ran into over the winter. From both a diabetic and nutritional standpoint I'm in a much better place now.

All this experimentation does not solve the most annoying issue about insulin pump therapy however. Why doesn't the pump allow us to set an advanced rate reduction?!? If I plan on working out in the morning I need to change my basal rate pattern from pattern A to pattern B. Pattern B is a carbon copy of Pattern A except I manually calculate 30% of whatever basal rate I would have an hour before exercise (or in this case before I wake up). I'm constantly changing Pattern B's time intervals or basal rate. This extra step probably takes more calculation than any other I've had to make as a diabetic. It would be alot easier to program my pump in advance 5am rather than having to calculate the correct basal rate and time interval.


Scott said...

You asked why the pump doesn't allow us to set an advanced rate adjustment (reduction or increase, for that matter). I posed this question to Animas a few years ago, and they told me that it was in order to "protect" the patient! I thought that was a lame excuse, but at least they answered ... Medtronic responded by saying they "decline to comment"!

Brett said...

Yea, those answers are indeed retarded when you think about it. I can still make a mistake anytime I want by entering too many carbs, etc. etc. etc. Thats a worthless answer.

Anyway Ed, thanks so much for sharing. I imagine this information is invaluable to many Caroline grows up its going to be more and more invaluable to us too. I am slowly building a mental library of all these things.


Anonymous said...

this blog is so boring.

Anne said...

I also have the second basal profile that I mess around with constantly. Actually, right now I'm on levemir and enjoying it, but I will go back to the pump for basal at some point.

During my Ironman last year I effectively shut down my pump for 3 hours straight. I didn't realize I was doing this because I kept setting temp basal rates that were so low that basically my pump was off. This did not work well of course! I think this is a major factor contributing to me having to stop for 30 minutes during the run. As soon as I stopped, my BG started to rapidly rise. I felt *much* better when I took a small bolus and turned the basal up a bit.

Previously, the insulin-independent exercise-induced glucose uptake pathways had been emphasized to me, but the insulin-dependent glucose pathways are also significant (albeit smaller) during exercise. I have been trying to find a basal rate/levemir dose that is relatively constant that can see me through the whole race so that I am not constantly needing to worry about it. It can become very distracting.

One of my biggest surprises last year was how much more insulin I needed on the run, especially the 2nd half, than I had anticipated. I had been so afraid of going low...


Brett said...

Anne, you bring up a good point - the pumps always round down on those temporary %-based rates, so its probably good to run the numbers in your head ahead of time to make sure you are actually getting the flow you want.

Bad Decision Maker said...

interesting... thanks for posting about this (i was planning on leaving this post before i saw anon's comment, i swear! i really did think, hmm, interesting when i read it)

i'm bookmarking it so i can go back when i start doing more intense workouts again. winter + neck pain + pump problems + move have made me go from working out 6 times a week to about once, but i'm hoping to change that soon and maybe even do a short triathlon this summer. in the past i've had a lot of problems with pre-exercise highs and/or during exercise lows, so its good to read about your strategies.

Vinicius Santana said...

Hi, great post, even though the posting about dating and diabetes is my favourite!

Keep up the good work, its always good to hear that others are doing great in the same situation that I am. check I am Type 1 too, and Ironman triathlete