Type 1 diabetes and marathon - fueling and insulin doses

Start the race with highish bs. Ditch the pump altogether for the race.

This is a discussion for you and your endocrinologist, not a LR message board. Every diabetic has different carbohydrate metabolism and insulin needs and you could get yourself into some serious problems come marathon time without careful planning.

Runnermama wrote:

This is a discussion for you and your endocrinologist, not a LR message board. Every diabetic has different carbohydrate metabolism and insulin needs and you could get yourself into some serious problems come marathon time without careful planning.

This ^

And even with perfect plans, things don't always work out.

insulincoln wrote:

Those of you who like me have run a few marathons with type 1 diabetes, do you think you need to do something different compared to other runners when it comes to glycogen loading before and fueling during the marathon, except the obvious not to become hypoglycemic?

Do you keep your basal insulin during the race at a lower level to avoid hypoglycemia, or at a higher level to enable and maximize the carbohydrate usage?

With the caveat that I don't want to be providing you with formal medical advice on here because everyone's circumstances are different, this is a subject I have a lot of personal experience with and can share what I do.

The week before the race I up my carb intake SLIGHTLY to ensure that my glycogen stores are topped off. There is no reason go crazy the night before and binge on a crazy amount of carbs because you won't be able to store all of that. Just do what you have practiced before other long runs. Get into a routine and be systematic about this so you know EXACTLY how much insulin you will need to cover your dinner and pre-race breakfast. The last thing you need is to be experiencing highs/lows the night before or moving of the race because you tried something different.

I wear an insulin pump with continuous glucose monitoring and have studied the impact of running at different paces on my blood sugar levels. When you run close to VO2 max (like for a 5k) you are actually prone to experience VERY high-blood sugar because your liver is dumping its glycogen stores to power the effort as fat cannot metabolize quickly enough at those paces.

However, in a longer race like a marathon, your fat metabolism will play a much more important role and you won't experience the same blood sugar spike. In fact, I always need to drop my basal insulin rates dramatically (but not to zero) to prevent dipping into low blood sugar territory. I personally aim to start out a bit higher than normal (i.e. 180) with a reduced basal insulin rate and find that it will decrease gradually over the run until I finish at around 70. I would recommend experimenting with this yourself before the race. If you don't have a continuous glucose monitoring system, this will be harder but I would even bring a test kit with you on some long runs and take a few samples to see what's going on and when. Annoying, yes, but you will be thankful come race day.

I would also read this study which has conclusions consistent with my own experience:

Best of luck!

Some guy that likes clocks wrote:

Runnermama wrote:

This is a discussion for you and your endocrinologist, not a LR message board. Every diabetic has different carbohydrate metabolism and insulin needs and you could get yourself into some serious problems come marathon time without careful planning.

This ^

And even with perfect plans, things don't always work out.

As a diabetic runner I actually don't agree with this and think a messageboard like this is the perfect place to discuss these things. "Everyday" diabetes management is very different than trying to run a fast marathon with type 1 diabetes. I have found that many medical professionals don't really have a great grasp on this particular topic and the people that know best are other diabetics.

It it also a much much different metabolic situation for a diabetic that is running a 4-5hr marathon (like most the doctors probably speak with) vs. one that is well under 3hrs. You can't just stop and check your glucose during walk breaks along the way and eat whatever you want as you go. If your blood sugar is not in a tight range, you won't be able to perform. You need to have this sh** dialed in for race day and know exactly how your body is going to tap into different energy sources along the way and prepare for that.

I think having a forum for diabetics to share their own experience and tactics is actually incredibly valuable. Of course, you shouldn't just line up on race day and follow someone else's plan, but I think careful experimentation of what has worked for others (during long runs is the time to try this) is a great idea so you can refine for what works for your body.

Hiya, I haven't ran a marathon but like to race 1500,2 miles, 5ks, and sometimes 13.1. usually during races I only carry 4 glucose tablets in case, aids stations in longer races are usually every 5k so I can get more complex carbs within 20 minutes no prob, but so far haven't gone too low on a track, road, or trail race. If I went low in a track race I'd probably step off, knowing I wouldnt preform to my best ability..

I never wear my pump on runs or races, too bouncy and throws off my form. Even on longer runs 18-20 milers I don't wear it, though I may take a .6 unit dose prior just for the basal dose I'll be missing. I usually make sure I'm 130-180 before starting a run, and have eaten ~15-30 carbs and fats+proteins about 30-60minutes prior with insulin ofc. Given I may reduce the recommended dose for my carb ratio if I feel particular paranoid about going low, aka eat something out of the ordinary before my morning runs- which usually consists of either Oatmeal berries and nuts or eggs and 1-2 toasts :p

I've found consistency with what I eat and when I eat and when I run works best with my diabetes. As a student my schedule has changed a lot over my past 4 years, and sometimes it takes adjusting :p but it's a whole heap of fun when you can make it work and have solid BG numbers :)

Longer runs I may carry a gu in addition to my 4 glucose tabs, just in case I go low and want to complete my long run, the gu will make sure my blood sugar doesn't go low again during the run.

All else fail always wear ur medical alert stuffs, though I am bad at that myself, id say ur doctor will be very happy if you do :D stay safe out there and Goodluck ^.^

Ro wrote:

I never wear my pump on runs or races, too bouncy and throws off my form. Even on longer runs 18-20 milers I don't wear it, though I may take a .6 unit dose prior just for the basal dose I'll be missing.

Wearing the pump definitely can be annoying. I have experimented quite a bit with this to find the most innocuous way to do it. In my experience, what works best is to use a FlipBelt for the pump (https://flipbelt.com/flipbelt-zipper) and a couple glucose gels. I also use two safety pins to connect the belt to my shorts to prevent it from sliding around at all.

To clarify myself a little, I've had type 1 diabetes since almost twenty years and run six marathons - most a few minutes over but once sub 3 hrs, so I'm not a complete beginner when it comes to running with type 1 diabetes. The advice to discuss the matter with the endocrinologist and not the LR board was expected but as has been pointed out, there can't more than a few endocrinologists in the whole world that would have anything to say about it, since the research about glycogen storage/usage and fat/carbohydrate metabolism during physical activity like marathon running with type 1 diabetes is insufficient. Also, to find other marathon runners with both type 1 diabetes and some ambition to not just finish the race, I think you need to go to a forum like this.

Where I live, the Freestyle Libre (a flash glucose monitoring advice, which uses a sensor like the CGM, but a smaller monitor to swipe over the sensor to see the glucose value) is available and light enough to bring on a marathon. I'm on subcutaneous injection therapy, but will problably change to pump in the next few years when they get a little more automatic.

So, to the subject, as I see it you can handle the fueling during a marathon in two ways. Either way, making sure your glycogen stores are topped before the race is obviously wise.

The different approaches would be to either keep your insulin levels during the race at a minimum and take in carbs enough to keep your blood glucose above 80-100, or to keep your insulin levels high enough to enable the maximum carb intake your gastrointestinal system allows.

Considering the benefits of running on carb metabolism compared to fat metabolism the second approach with maximized carb intake sounds more appealing to me, and what I've tried to do during my last marathons.

But even with generous intake of gels and sports drink I feel prone to go empty and loose speed during the last five-ten miles, and I feel I'm more sensitive to this compared to nondiabetic runners.

Any new input?

diabetty wrote:

Any new input?

I also would love more information as I am a type 1 diabetic and training for my first marathon. I am training for a 3:15 first marathon and want to make sure my diabetes is managed well for it.

Any info would be great!!!