After a lot of trial and error, I have finally been having some good success managing my blood sugar during intense cycling efforts such as at criteriums, circuit races and time trials. This is very exciting to me because at some points last year, I was at my wit's end with race-related blood sugars severely high enough to not only hurt my performance but also to raise my A1c slightly.
In general terms, I pre-program my pump basal rate to increase by 30%, beginning an hour before I plan to eat breakfast, and I time my breakfast to be no closer than 3 hours before the race start. So, for example, I started my 30% increase at 5 AM this morning and ate breakfast at about 5:50, in anticipation of my 9:00 AM time trial (TT) start time. I ate a normal breakfast and took my full bolus plus a small correction for a 164 BG. (I actually bolused about 15 minutes before I ate, at 5:35 AM. In general I like to take a meal bolus as far away from my race as practical, while not eating so early that I'm hungry again before I race.) I pre-programmed my basal rate to be +30% throughout the duration of my race. I prefer using increased basal rates versus extra boluses because, in the case that I give too much insulin, correcting for the former is much easier.
Once onsite, I got all my stuff ready, rode about a mile to registration and back, and got ready to start my warmup on the trainer. By this time (8:15 AM) my BG was hovering around 100 so I ate 34 g carbs (clif kid twisted fruit ropes, which seem relatively easy on the BG); since I was about to warmup, I expected that effort to keep me from rising too much, as well. I only had time for about 30 minutes of warmup, and checked in with a BG of 89 ten minutes before my race start time. I ate one clif shot energy gel and could see my BG was starting to rise, so tucked another gel under my shorts and went to the line. (I also had 2-3 gels in my jersey pocket because, well, you never know.) My instinct, when I see a BG of 90 that close to a race is to overreact and eat too much; it has been hard for me to learn to trust that the adrenalin will really kick in (especially with a +30% increase in my basal rate).
Since I have been using the Dexcom 7+, I rarely bring my blood glucose testing kit with me on rides of less than a few hours; and it really is very impractical to test during a cycling race. My confidence in the Dexcom CGM technology has grown tremendously compared to the first STS sensor years ago. (I think anyone who used that remains a bit cautious; but I am quite impressed with the current version.) For races, I set all of the alarms on to sound plus vibrate; I also set the low alarm at 100, the high alarm at 200, and the rising/falling alarm at 2 mg/dL/min. Sometimes I can feel the CGM vibrate but usually I hear the 2 or 3 tones that tell me whether I am high or on the rise, or low or falling, respectively. (I really wish the low and high alarms were fully customizable; actually I wish the number of alarms was also customizable and that there were more sounds to choose from. I really want to know when my BG is below 120 or I may have some other arbitrary target. Actually, what would be even better is if it were displayed on my bike computer screen. Can the Dexcom transmit ANT+ please?) Anyway, for today's race I could hear that I was rising; although at the time I assumed I was high since the alarms are the same. The CGM graph showed that my BG rose throughout the race but peaked at around 180, which I'm pretty happy with. It was still on the rise until after I finished racing.
I've used this approach for the past couple races now, and I am slowly beginning to trust it; although I realize there may yet be a better strategy. In some ways, it is similar to the challenges I had during T1 (transition between the swim and bike) in half- and full-ironman distance triathlons. Believing that a 400 BG after a significant swim plus hour on the bike is due to my own hormonal response, and not some fault in the insulin delivery or some other wacky unknown, took some experience. And believing that I could really increase my basal rate during the swim (or end of the swim) took some trial and error as I gradually increased my confidence that I wouldn't go low. If insulin didn't cause low blood sugar, this would all be so much easier, no?
Oh, and for today's race, I came in 4th place for the women's 4 field. Race reports that may describe more of the race details can be found on the Team Type 1 website.