Another marathon down(my third)! And a new personal record! My time of 3:47 at the Philadelphia Marathon was a two minute improvement.
This race is an important point in my 2012 Quantified Self project. In order to best learn from the day, I carried a total of 8 devices with me: an insulin pump, 2 continuous glucose monitors (CGM) (a Dexcom 7 and my newly arrived Dexcom Gen4), a standard blood glucose monitor, a Garmin heart race monitor chest strap and GPS watch, an iPhone, Nike FuelBand and FitBit. I’ll talk more about these later.
As for my diabetes, managing my blood sugars on the day of the race turned out to be more of a challenge than I was hoping for. During my two previous marathons, I saw my blood sugars spike in the hours before the race, both from being anxious and from how i managed my meal dosages. I was determined to prevent that from happening again this year. I had a normal breakfast (an english muffin with almond butter and a banana) very early in the morning at 5am in order to get to the start line on time. I took a dose of insulin that I would normally take assuming I wasn’t about to exercise. I then had another half of an english muffin at 6am. I took a smaller dose for this, hoping that my blood sugars would start going up a bit closer to the 7am start time (they had been at about 145). I also began a temp basal rate at 6am, setting it to 20% my normal rate for 3 1/2 hours.
But starting just a few minutes after eating around 6:15, I saw that my CGM was showing an arrow headed straight up. That means that my blood sugars were rising quickly. Outside of the food considerations, I was nervous before the start of the race. It was just normal pre-race jitters. I may have run marathons before, but I haven’t done them enough that I can approach 4 hours of exercise casually.
I took a little more insulin right away. Closer to the start, I looked again and my blood sugars were still rising quickly. They were now over 200, with the arrow on the CGM still pointing straight up. Frustrated, I took another dose of insulin. By the time the race finally started around 7:10, I was at about 240 and not feeling great. When my blood sugars get that high, I definitely feel sluggish. It was disappointing to think that 18 weeks of training can be tripped up by this.
About a half hour into the race and, I started to feel better. I had more energy, was finding my stride and felt like I could focus on the experience instead of worrying about my blood sugars. Around 8am, I tested again and was surprised to see that I was already down to 123. Sure, that means that I was back in range. But for it to drop this much this quickly was not a good sign. There were several units of insulin on board, meanning that I could expect my blood sugars to continue dropping for another 1-2 hours. I took my first exercise gel (a Hammer brand, espresso flavor one with 22g of carbs). These are good for the energy and also normally give my blood sugar a little spike. Along the route, I also decided to switch from drinking water to drinking Gatorade. The cups are not that big, but I figured each has at least a few grams of carbs.
At about the two hour mark, I tested again. My blood sugar was now 88. Still lower, but not dropping as fast as before. I took another gel. Normally on long runs I take a gel about every hour and am able to keep my blood sugars stable. But a half hour later at 9:30 I took another because my blood sugars were now around 80, lower than I wanted. I would much have preferred they be in the 120 – 140 range. At 10, they remained at about the same place, so I took another gel, hoping that would finally do the trick.
The whole race reminded me of a long training run I did this summer where it seemed like no matter how many carbs I took, my blood sugar would not go up. It is really frustrating. Had I been running through the city, I may have pulled over and had a small bottle of orange juice. But along this route, the gels were the only thing I had brought along to keep me level. But in addition to the lows, I was also a little worried about overdoing it and causing another wild swing up. From that run this summer, I remembered that my blood sugars spiked just as I was finishing. I was taking all of this into account, trying to nudge them up, but not too much. I finished with a reading of 114, perfectly in range. A frustrating start, but a great ending.
As for the run, I certainly can’t complain too much about a new personal record. Yet I do think that I went out a little too fast. I ran the first half at a pace about 15-30 seconds/mile faster than I should have. I definitely paid the price the last hour. I hit the wall right around mile 20. By mile 24, my pace was a full minute slower than earlier in the day. But I finished! Lesson learned, for sure. Pacing yourself effectively is definitely a skill. Something for me to work on in the future.
As I mentioned earlier, I had 8 devices on me to gather more information about the race. In particular, I added to heart rate monitor after speaking with a fellow type-1 diabetic in Colorado named Jochen Wendel. He is completing his Ph.D. at the University of Colorado focused on cartography. In recent months, he has begun looking at the correlation between blood sugar, heart rate and GPS data. He is an avid bike rider. Being out West, many of his rides have significant changes in altitude. He has also been using his own data as the basis for exploring new approaches to diabetes care. We are looking to sort through my data together in the coming weeks and see what we can find.
Jochen also has data from a long international flight he took back to the States. After accidentally leaving his heart rate monitor on during a flight, he used the opportunity to consider jet lag and its effects on blood sugar. It just so happened that I had two long flights just before the marathon. On Thursday the 15th, I flew from NY to SF to attend the DiabetesMine Innovation Summit the next day. 27 hours after landing, I took the red eye from SF to Philadelphia, landing the morning of the 17th. That gave me one day of rest before the race on the 18th. I kept the heart rate monitor on during both flights. I’m interested to see if anything can be gleaned from this information as well.
As for the rest of my data and devices, this information will all be included in my thesis next year for ITP. It’s been interesting to collect information throughout all of 2012. I am excited for the new year and being able to start the next phase in the process. That will include parsing the data, spotting the trends and developing ways to visualize the hundreds of thousands of data points. As for my data between now and the end of the year, I plan on exercising very little. I am interested in seeing how my body adjusts to this new pattern, especially my insulin basal rates.
All in all, between the DiabetesMine Innovation Summit in SF and the Philadelphia Marathon two days later, it was a busy but exciting few days!