On Saturday, I pre-programmed my pump for the race the next day, based on my predicted times for each leg of the triathlon. Typically for a race, I will program an increased basal rate before my planned breakfast time in order to help counter my tendency to run high on race morning. For an Ironman, this is typically about 4 hours before the race start. About an hour before the swim start I might drop it a little from normal; I don't need to drop it much because my basal rate is pretty much set to keep me stable during morning exercise. I'll keep it slightly lowered during the first hour of the swim, and then raise it quite a bit about 30-45 minutes before I get out. The reason I do this is because I consistently have a spike in my BG at the start of the bike. I have had races where, within one hour of starting the bike, my BG has gone from upper 100s to over 400, even with eating very little to no calories. I believe this is due to the high level of excitement (and therefore increased adrenalin) that naturally occurs in the transition between the swim and the bike. I'll keep my basal rate raised (say from my normal 0.6 to 0.7 units/hour to 1.0 or more) for the first hour or two of the bike, and then drop it down to a level that has worked for me in training on the bike, given my planned calorie intake. An hour or so before the run, I'll drop it down lower, to a level that has worked during training runs, especially those that had followed a long bike ride. I may also eat a little extra in the last hour of the bike. During the run, I often have to do some trouble-shooting it seems, but try to settle into a good level as soon as possible. After the race and overnight, I set my basal rates back to normal or to slightly reduced levels.
For me, this strategy has worked well, especially if I have done a lot of testing during training to get really comfortable for what rates work well for me. I try to get familiar with the actual numbers, rather than just a percent increase or decrease. Still, it is hard to predict how my body might react to the increased stress and duration of exercise on race day, especially after a week of tapering. I tend to err on the side of letting my BG ride a little higher rather than increase my chances of having a low BG, which is really painful during an Ironman. Although, having high BGs during a race is no picnic either.
Regarding bolusing, I will take my normal breakfast bolus 3.5 hours before the race start to give myself time to correct for post-meal highs, and to give the bolus time to taper off before starting the swim. I am still learning how much I can bolus during an event without crashing later. Correcting for highs on the bike seems easier, and I have more recently learned that I can manage with a couple units of insulin on board without my blood sugar crashing. I get really nervous taking big boluses, even to correct for severely high BG, during exercise. I just hate so much having low BG during a race. It really destroys me, physically and mentally. Although I have also learned that I seem to recover okay if I am patient when I have a low.
Record of my diabetes management during IMAZ 2009
(Thanks to Kevin for his Excel logbook, which can be found here.)
(Thanks to Kevin for his Excel logbook, which can be found here.)
At 3:30 AM, 3.5 hours before the race start, I bolused 4.5 units for my 65-g carb breakfast. About 1.5 hours later, my BG was good at 165, but then started to climb before the start. I was surprised to see it rising up through the 200s and then spike at 303. I skipped my pre-race gel/Gatorade and decided to correct with 0.3 U before getting in the water for the swim start at 7 AM. During the first half of the swim, I felt good, but started to get hungry about an hour in; after some internal debate I ate a gel, which gave me confidence, and finished the swim at 182. I started the bike around 9 AM and was really hungry right away. I ate a few bites a few miles in and before checking my BG again, trusting that my basal rate of 1 U/hr since 8:30 had been enough. Unfortunately, I popped up to 349, so went ahead and bolused 1.4 units. This gradually brought me down to the 180s and then 130s about an hour before the run. I started the marathon at 139 and promptly dropped to 53 in the first 2-3 miles. It took me some time to recover from this and I was shocked at how high I had set my basal rate! What was I thinking? Anyway, I temporarily shut off the pump for 30 minutes and set my basal rate at 0.2 U/hr. This seemed to work for a while but then I had an unexpected, enormous spike in my BG; I think this was the beginning of the third loop. I wondered if the pain was stressing me, causing the high BG? Or probably the slow pace was requiring fewer calories? Did that chicken broth have a lot of calories in it? I took about 2 units but this high was stubborn, and I had to take another unit of insulin. I was over 400 for about an hour. Yuck. I drank lots of water, took some salt tabs to replace depleted electrolytes from the high. I eventually came down and then relied on the cola to keep me from bottoming out. I didn't check right after finishing, but had come up to 242 about 45 minutes after. I bolused for the pizza I ate and went to bed a little hungry, and woke up with a BG of 63 early the next morning. But otherwise, I didn't have any issues with low BG following the race.
Next time, I would keep my increased early morning basal rate until 6:30 AM, rather than 6; or perhaps I would raise it from 0.8 to 0.9 (above my normal of about 0.55 that time of day). For me, it's easier to treat a too-high basal rate than a bolus over-correction. About 30-45 minutes before the swim finish, I would increase my basal rate even higher--maybe to 1.5-2 U/hr--and would keep it there for about an hour on the bike. Or else, I could take a couple units as an extended bolus in T1, which would have the same effect but would be timed a little more precisely with my race. I used to use this method but felt like it was less to think about to pre-program my basal rates. Also, I think it works better for me to have increased insulin on board before I get out of the water. For the run, I could have lowered my basal rate earlier before getting off the bike, and should have lowered it more. It was essentially the same as it would normally be at that time of day, if not higher! I had based this on a level I've used for long training runs in the past but at a different time of day and not after a long ride. I need to keep my wits about me and realize that, if my pace is really slow, I am probably not burning as many calories per hour, so probably will need more insulin. I think my strategy next time might be to drop my basal to something like 0.2 units/hour before the run start and then increase it a little to 0.25 or after an hour or so of running.
I'd like to believe that I can figure it out once and for all and then have perfect insulin and BG levels at every race! But I think, for me, it is more realistic to expect a certain amount of fiddling. There are so many variables, new and old, to consider on race day. I definitely feel that, after several years of experience, I can anticipate a lot of the tricky spots during a race; and, even when things don't go perfectly (which is always the case for me, it seems), I have less fear and anxiety over it all.
(Stolen from an earlier post of mine...)
For those who are less familiar with diabetes terms, here's a primer. BG refers to blood glucose, which increases with food intake (especially carbs) and stress, and decreases with insulin and, often, exercise. Sometimes exercise can cause the BG to increase, and many other variables affect the rise & fall of BG. Insulin takes the glucose from the blood and helps to shuttle it into fat & muscle cells. Insulin must always be present and can be delivered through injection or insulin pump. I use an insulin pump, which delivers a "basal rate" of insulin throughout the day. I program this depending on my activity level; basal rates also change throughout the day. For me they are highest in the morning and lowest in the afternoon. When I eat a meal, or need to correct a high BG, I take a "bolus" which is basically like an injection except it's done with a pump.