Tips on Glucose Management During and After Exercise
for Type 1s

You may never have heard their names before, but they’re out there and they’re dominating in almost every sport: basketball, football, surfing, car racing, Olympic snowboarding, Taekwon-Do and even ballet. Sean Busby, Zippora Karz, Charlie Kimball and Missy Foy are just a few professional athletes living out their dreams and simultaneously living with type 1 diabetes.

Even though shooting for an Olympic medal is not the norm for most of us when we lace up our running shoes, the success of those who have can bring inspiration to people with diabetes who want to keep fit at any level.

A ton of research is being done in the field of glucose management during and after exercise, and we asked two top researchers who are also athletes living with type 1, to provide insights into their work and to share their personal training regimens.

Dr. Michael Riddell is a Professor in the School of Kinesiology & Health Science at York University in Canada and is considered the international authority on exercise and stress hormones and how they affect diabetes metabolism. He enjoys biking, hiking and trekking, and climbed Mt. Kilimanjaro in 2013 with the World Diabetes Tour.

Dessi Zaharieva is a 3rd year PhD candidate in kinesiology and health science at York University. She earned a bronze medal in Taekwon-Do at the 2013 World Championships and is currently training and competing in mixed martial arts. Her research at York is aimed at improving diabetes management and blood sugar control during exercise in individuals with type 1.

TCOYD: Do you have any advice or tips for someone with type 1 who wants to take their training to the next level or take on a new fitness challenge?


Unfortunately there are no magic bullets or magic solutions…what we’ve noticed is that training for an activity with type 1 requires a lot of vigilance around glucose monitoring along with a lot of trial and error.


General guidelines are difficult because individual variability is so huge. For me, even if I were to do the exact same things today and tomorrow, the exact same training with the exact same adjustments to my sensor-augmented pump, I may not have the exact same response.

Also I have to take my pump off during training because I do mixed martial arts and I fight, so the changes I make to my pump might be very different than what Mike does when he’s cycling, because he doesn’t have to disconnect his pump.

TCOYD: Can you share some things that have worked for you personally with regard to managing glucose levels while working out?


For the prolonged endurance exercise that I do that lasts an hour or so, I need to get my insulin down beforehand, so I try to find a time to do that activity when my insulin is already low, and the insulin I’ve taken after a meal is largely gone. This can be four hours after a meal or more, or it can mean exercising in the morning before I have breakfast. That really is the key to my success.

On top of that, I need to lower my basal insulin on my pump well in advance of an endurance activity, so an hour or 90 minutes beforehand, I need to get my basal down to about 20% of my usual basal rate. I also have my CGM on to make sure my blood sugar’s not getting too high.

I can usually get my basal rate down aggressively and then I can go for an hour – two hours even – with a very long run or a long bike ride. My performance improves if I can then start to have a little bit of carbohydrate from either a sport beverage or glucose gels, but I might need to turn my basal back up a little if I notice on my CGM that my glucose is beginning to rise because I’m snacking.

So for me, the secret is starting with low insulin in my body and then consuming carbohydrates for performance at the rate of around a half a gram of carb per kilo of body mass, so around 40 grams an hour or so.


With my training there are a lot of similarities to Mike in that we both reduce our basal insulin quite drastically beforehand because I feel like without doing that, too much insulin in the circulation is not going to be a good thing with the amount of training I do. My training sessions are between one and three hours a night and sometimes even longer.

With that amount of exercise, reducing basal insulin becomes very important (or just having less insulin in the circulation if possible). That is one of the times when preplanning is essential. I don’t like to go fully fed into a training session. If I can wait four hours before I train that’s the best situation – to not have a lot of food or insulin in the body in order to try and prevent big spikes and drops in blood sugars.

TCOYD: How often are you checking your blood sugar during a workout?


I’m vigilant about monitoring my glucose and constantly using CGM, and I wear my CGM on my watch. I don’t stop and poke my finger and do a blood test – I’m just looking at my outputs on my watch or on my pump, and I look frequently because I know my performance is best if my glucose is near normal or only slightly elevated. In American units I’m talking about 120, 130 milligrams per deciliter. That’s where I want to be, so I’ve got to look at my CGM all the time so I can continue to make changes. I can increase my basal rate if my glucose goes high or I can snack on carbohydrates if it drops below that narrow window of performance for me.


My pump is off when I train so it’s not as easy for me to check my CGM. I have the new Medtronic 630 G pump. I keep it in my bag really close to where I train, and anytime we get a water break I go look at my pump screen and it picks up a signal as long as I’m not too far away. So even if it’s not connected to me I still have an idea as to what’s happening.

TCOYD – Are there challenges in glucose management post exercise?


It can be really challenging to maintain blood sugars throughout exercise AND in recovery. That’s one of the biggest challenges right now.


Some of the research we’re doing is focused on the glucose excursions and the meal after exercise, and if you have your pump off whether that makes glucose go higher. During exercise everything may be okay, but you may suffer a little bit in what to do for the meal after exercise if you’ve had your pump off, you’re hungry and you want to have a big meal, but your insulin might be low at that point.

Recovery is important because if you want to feel good and do it again the next day, you have to treat your body well in recovery. We’re still learning what the best approach is, what the right meal is, when to eat, how much insulin to give for any given meal, etc. You know you use a lot of calories and you burn a lot of carbohydrate when you exercise, and you’ve got to pay it back or you’re going to possibly set yourself up for hypoglycemia overnight. So these are all interesting research questions that we’re working on right now.

TCOYD: What are your thoughts on taking Afrezza if your numbers are high after a workout?


We have Fiasp here in Canada. We don’t have Afrezza, but we know athletes who have taken Afrezza after seeing high blood sugar, and it disappears out of the system quite quickly which is nice, and then there’s no prolonged late onset hypoglycemia so I think it holds some promise.


We know that if we can get the insulin in our system faster it’s going to help.


Get it in and get it out!


I’m going to have spikes if I don’t take bolus insulin after exercise with my pump disconnected for so long and if that insulin is taking half an hour to actually start kicking in and working it’s already too late, so the Fiasp has been very helpful.

A few final thoughts:

People with type 1 diabetes can achieve basically any dream they have on the exercise front. They can be Olympians, marathon runners, rugby players, basketball players, etc, but each form of exercise has different energy needs and places different demands on their diabetes.

If you are embarking on a new goal or simply focusing on maintaining a current one, remember that it’s process of trial and error, try not to get discouraged, and what’s most important is that you do what works best for you and your body.


For more information on exercise with type 1, check out Dr. Riddell’s book:

Getting Pumped- An Insulin Pump Guide for Active Individuals with Type 1 Diabetes
available here.

For more information on their research at York University, please visit Dr. Riddell’s webpage here.  

  1. Avatar

    My daughter and I were attempting to follow up on ultra marathoner Melissa Foy My daughter is distandane runner with Type 1 and is experiencing some of the same ailments as Mellissa was in 2016 but Melissa stopped posting on her blog in 2016. Is she oka?

  2. Any plans to do a similar post about marathon runners and other endurance athletes with Type 2? We have a lot of special requirements for fueling and managing glucose levels for long bouts of exercise, too, and there is almost no information publicly available to help.

  3. Appreciating the time and effort you put into your website and in depth information you offer. Very inspiring and clear explanation! You’ve really covered up almost all the possible info that every fitness enthusiast and health-conscious person should follow who is so curious to stay fit and healthy. Worth sharing! Please continue sharing your updates! Thanks a lot!

Leave a Reply