How to be competitive in endurance sports with diabetes type 1?
I’m Rob, a citizen from Belgium, and in May 2009 I was diagnosed with Diabetes Type I at the age of 22. It came as a big shock because I had no idea what to expect and I had many unanswered questions like “Do I always have to inject insulin 5 times a day - Do I always have to weigh my food from now on - Can I still do competitive sports”. I was worried I couldn’t do sports like I did before. Doctors immediately said I could still do sports, but not too much, and doing endurance sports would be nearly impossible. With a lot of questions doctors couldn’t answer, I started to train for a full distance triathlon after I graduated as master in biology. I tested my blood sugars 8-10 times a day and wrote everything down. Sometimes my blood sugar was too low or too high before, during or after training, so afterwards I knew what I had to change the next day to get my blood sugar where it has to be. After 7 weeks of training I had figured out how much insulin I need during race, how much carbohydrates I have to eat each hour and when and how much I have to drink. Two and a half months after I was diagnosed with diabetes I finished the 3.8km swim, 180km cycling and 42.2km running and became first in the category under 23. Since then, I started to train very intensively, coached by Loïc Hélin – Belgian Champion triathlon in 2007, trying to be a much more competitive athlete. I was able to get normal blood results and managed to get an HbA1c level of 5.9%. All the effort on training, 25-32h a week, didn’t really pay off in the beginning. I mainly struggled from cramps in my stomach during races. Diabetes doctors couldn’t help me. I tested different food and tried to find out if small injections of Levemir® (~10U) would relieve me from these problems. Unluckily, at the European Championship half Ironman I suffered again from cramps in my stomach and became 17th in the age-group under 25. After this race I had my hands in my hair searching for someone who could help me. Luckily I came in contact with the Royal Doctors, and they send me to Prof. Harry Dorchy at the Koningin Fabiola Children hospital in Brussels. He’s known to be a very successful endocrinologist, especially working with young children but also with competitive sportsman like Pär Zetterberg, a former professional soccer player who played in the team of RSC Anderlecht (Belgium) for several years and earned ‘De Gouden Schoen’ price as the best player in the Belgian soccer competition in 1993 and 1997. When I came to Prof. Dorchy, he immediately did some tests to find out if I was still producing a little amount of insulin or not. He concluded I still produced a little bit but not significantly to speak about a “Honeymoon Period” - a period after diabetes is diagnosed where you still produce a little amount of insulin which will still help you to control your blood sugar. Prof. Dorchy gave me the opportunity to make use of a continuous glucose measurement (Navigator®) which measured my blood sugar every 5 minutes. In the 8 days I was making use of it, I never went below 70mg/dL and never above 180mg/dL, also not during my run and cycling trainings. I was planning to do a half distance triathlon using the Navigator so I could see if my blood sugar was still under control during races. Sadly, the Navigator couldn’t be used under water. So until now I have no results of my blood sugar level during triathlon races. The VEO from Medtronic would be a nice tool for me to check out my blood sugar during races. But this machine is still not on the market in Belgium. Prof. Dorchy was surprised about the fact my blood sugar level was so balanced day in day out and he told me he had never seen these good results before. He told me I didn’t really have to change anything to be as competitive as non-diabetic sportspeople.
Figure 1: Difference between a diabetic and non-diabetic person in their insulin levels and glycogen concentration in their muscles during an Ironman race (Hypothetic). The blue dotted line indicates the insulin level of a diabetic person with no insulin injection, the purple dotted line indicates a hypothetic insulin level of a diabetic person after injecting 20U of Levemir® at 4am, and the yellow dotted line indicates the normal insulin level of non-diabetic athlete having breakfast at 4AM. Ironman race starts at 7am and in this example the 3 athletes finish at 5pm. During an Ironman race, a non-diabetic person should have a stable level of insulin (indicated with the red arrow) caused by eating and drinking regularly (about 1.0-1.2gr carbohydrates/bodyweight/h). The full lines indicate the drop in glycogen concentration in the muscles during an Ironman race. You can see the glycogen concentration drops more rapidly when no insulin is injected (blue line), in comparison with higher amounts of insulin (purple and yellow line). The purple collered area indicates the gain in glycogen concentration after injecting 20U of Levemir®. The basal insulin level of the non-diabetic athlete (indicated with the red arrow) is resulting in a much higher glycogen concentration (yellow collered area).
2 months later, on 28 November 2010, I finished 6th in the age-group under 25 at the Ironman of Mexico Cozumel, without injecting insulin before or during the race. Although my blood sugar level is always under control, I had many questions after this race which couldn’t be answered yet. Looking ahead for my next big goal, Ironman Lanzarote on 21 May 2011, I was trying out if I could perform better having a little amount of Levemir® injected. I injected 20 units 3 hours (4 AM) before the start of the race (Look at figure 1 for details). Although I finished the race in a little bit more than 11 hours and came 15th in my age-group 25-29, I wasn’t so happy about my result. The main problem I have, after finishing 5 Ironmans, is that I have the impression the sugars I eat before and during race don’t go fast enough to my muscles. I eat 1.2gram carbohydrates/bodyweight/hour which means I eat nearly 1Kg of sugar during the Ironman. If you take a closer look at figure 1 you’ll see that my insulin level could be too low to carry all my sugars to my muscles. How much insulin (for example Levemir®) do I need to inject to reach the same basal insulin level as non-diabetic people have, assuming they all eat 1.0-1.2gram carbohydrates/bodyweight/hour? At the moment I’m looking for someone who wants to help me how I can bring these sugars to my muscles in the most efficient way.
Secondly, figure 1 also shows the relation between insulin level and glycogen concentration in muscles. It is very significant my insulin levels, both at Ironman Mexico and at Ironman Lanzarote, were too low resulting in a fast drop in glycogen concentration. The most serious damage I made to my glycogen level was in the swimming part where I could not eat or drink for 1 hour. Figure 2 shows the drop in power on the bike after the glycogen concentration went below a threshold. The lower the insulin level, the faster the glycogen concentration drops and the sooner the glycogen threshold will be reached. You can see some serious drops in power output on the bike (blue and purple lines) after the glycogen concentration went below the threshold. By injecting 20U of Levemir® at Ironman Lanzarote, I was able to postpone the point where the glycogen level reached the threshold. The glycogen concentration of a professional triathlete never went below the threshold.
Why getting cramps?
At the moment I’m training very intensively for about 1.5 year now and never had a race without stomach cramps, with exception of Ironman Mexico. The fact I don’t have measurements of my blood sugar level during race, makes it hard to find a solution for my problem.
Figure 3 pictures three possible reasons why I’m getting cramps, two of which could have been figured out by using a VEO continuous glucose measurement. The first scenario (Figure 3-1) I’m getting cramps from a bad digestion, which is the result of a low blood concentration around my stomach and intestines. A lot of triathletes struggle from this problem at the beginning of their careers. Does my body still need some adaptation time to match doing endurance sports and having a good digestion? The other two scenarios are related to my diabetes. It is possible my insulin level is too low. If I eat 1.2gr CHO/Kg/h during a race, I will get a hyperglycemia because the sugars in my blood doesn’t go fast enough to my muscles. I will get stomach cramps and my muscles will get exhausted very fast. Figure 2 confirms this scenario could be very reasonable. The last scenario (Figure 3-3) is related to my fast metabolism. Is it enough to eat 1.2gr CHO/Kg/h during a race? Maybe I’m burning a lot of calories, due to my fast metabolism, I might need much more sugars. If not, my muscles will get exhausted as shown in figure 2 where my power output on the bike drops. My fast metabolism could be the reason my blood sugar level drops very rapidly during a 1h swim where I could not eat. This will result in a hypoglycemia where I will get stomach cramps from.
Figure 2. Glycogen concentration in muscles in relation with power output on the bike. The 3 graphs show the power output on the bike during my Ironman of Mexico (blue line), my Ironman of Lanzarote (purple line) and of a non-diabetic professional athlete (green line). The dotted lines indicate the drop in glycogen concentration during cycling. At Ironman Mexico I didn’t inject insulin, at Ironman Lanzarote I injected 20U of Levemir®. At Ironman Mexico, the glycogen concentration drops rapidly and the threshold is reached already at 10AM (red arrow), resulting in a drop in power output from 10AM to 1PM. At Ironman Lanzarote, the glycogen concentration drops less rapidly and crosses the threshold at 11.30AM (red arrow). The glycogen concentration of the professional athlete (green) never went below the threshold and was able to keep pushing high power on the bike. The yellow areas indicate the time the athlete still has the power to put high numbers of watts, which is related with the drop in glycogen concentration in their muscles. And as seen in Figure 1, glycogen concentration is related with insulin level.
Figure 3. 3 different scenarios why I’m getting cramps during races. (1) First scenario shows that at high physical intensity, the oxygen rich blood goes to the muscles and the blood will not be concentrated around the stomach and intestines. This resulting in a bad digestion when eating 1.2gr CHO/Kg/h and cramps will occur. (2) The second scenario shows the low insulin concentration as the main factor getting cramps. At high physical intensity, muscles burn a lot of calories. Trying not to exhausted the muscles too soon, I have to eat 1.2gr CHO/Kg/h. When my insulin level in blood is too low, the transfer rate of these sugars to my muscles will be too slow and I’m getting a hyperglycemia and stomach cramps will follow. (3) The last scenario getting cramps is the result of my fast metabolism. If I have a very fast metabolism, eating 1.2gr CHO/Kg/h wouldn’t be enough to feed my muscles, assuming I have normal insulin levels. The cramps always occur after swimming where I could not eat, due to the heavy physical intensity during the swim, together with a fast metabolism. This results in a hypoglycemia where I will get stomach cramps from.