Managing Diabetes and Exercise – Avoiding Low Blood Sugar

When I first got my insulin pump, I thought exercise would be easy, but it actually took a lot of trial and error to figure out how to go on a bike ride or a walk without fearing a low.

For many people with LADA Diabetes and Type 1 Diabetes, with increased activity, the chances of experiencing hypoglycemia increase. It can be a struggle to stay in range because blood sugar can crash pretty fast from exercise! Muscles have GLUT4 proteins which bring the glucose into the muscle cells, so insulin sensitivity goes way up when working out.

It is definitely possible to exercise, play sports, run marathons, take hikes, etc, even when you’re managing you blood sugar with insulin. It takes more planning, but it’s worth it, because physical activity is paramount to good health. It also can really improve mental health. And improved mental health can also improve diabetes for a number of reasons, a big one is that stress hormones increase insulin resistance. It really is all connected.

Please don’t give up your exercise! Instead, be prepared and keep trying until you figure it out. If you have a Continuous Glucose Monitor (CGM) that makes life a lot easier because you can see the trend, instead of just a single number.

How to not have hypoglycemia when exercising?

Well, the solution I’ve been trying is to only exercise when there is NO INSULIN ON BOARD! “Insulin on board” (IOB) refers to the amount of bolus insulin that is still active and is shown on my pump as “Active insulin.”

Exercise before Breakfast

Early morning exercise is the easiest to plan for. As soon as I get up, I set it to the temp target of 150 mg/dL. About an hour later I head out the door. At this point, I have no insulin on board and the temp basal rate, plus the natural morning hormones, are causing my blood sugar to rise.

This is called “fasted exercise” and depending on several factors, such as the duration of the exercise and my starting blood sugar, I may not need to eat anything to keep my blood sugar in range.

On my previous insulin pump model, I used to suspect the pump as well, but lately I’ve been finding that temp target works well. Discuss with your doctor if you need guidance on the best setting for your pump.

It’s also possible to do fasted exercise if you use insulin pens instead of a pump. The key is getting your basal rate dialed in. I used to do this. I would exercise before doing my morning injection. Definitely work with your doctor on any insulin adjustments.

The tricky part is that after this early morning exercise, I’m usually quite hungry! My blood sugar tends to rise after the exercise and if I don’t get the insulin bolus just right, I may end up with high blood sugar after eating breakfast. Patience is helpful here.

Exercise After Lunch

This can be challenging, because any insulin taken with lunch will be active and it may cause a quick drop in blood sugar as the muscles use up the sugar. If I know I want to exercise after lunch, I may take a half dose of my mealtime insulin dose, or even no insulin at all. However, I usually can only manage skipping the insulin altogether if I eat a low carb meal. Otherwise, I’m likely to go high for some time period before the exercise kicks in.

Exercise in the late afternoon

In the late afternoon, I can manage to exercise with little or no insulin on board. At this hour, most of my lunchtime insulin has worn off, and this is before my dinner time insulin bolus.

However, I have to wait quite awhile to get to 0 insulin on board, so sometimes I walk with like 0.2 insulin on board. In these cases, I often need something with sugar in it, or I go low.

Fruit gummies are my preferred low blood glucose treatment.

Planning is worth it

If I don’t plan for exercise, then I tend to have low blood sugar, and that takes the fun out of exercise.

Blog Entry: A Bike Riding Success Story

The following was written some years ago and recounts my excitement with figuring out how to have a nice bike ride without diabetes stress.

Today, I biked for an entire hour and my blood glucose stayed in range! I am feeling good about the increased exercise and about the success at managing my diabetes while cycling. Bike riding is something I’ve been wanting to do again, but it was difficult to do because my blood glucose would drop quickly from the exercise 🙁

I actually have been wanting to bike ride for over a year and a half, since I first got my insulin pump, but exercising has been super challenging because I can get hypoglycemia quickly. Nothing causes a blood glucose drop as fast as exercise. ⬇️⬇️⬇️ Three arrows down, if I’m not careful…

Recently, I’ve had some success, as I’ve been bike riding about 40 minutes at a time, and today was the first time I increased this to over an hour.

I feel like a novice here, as my strategy is simply to keep trying… and work on improving my management and techniques each time.

What I did before Bike Riding

• I did not bolus in the morning before bike riding.
• I set my insulin pump to Temp Basal (Exercise mode) so that it would give me less basal insulin before the ride.
• I drank a chocolate milk and a rather large glass of orange juice. I estimate at least 50 carbs. No bolus for these.
• I packed my backpack, and made sure that I had three juice boxes and plenty of candy, just in case. During past (shorter) rides, I drank one juice box when I started to see my blood glucose trend down. I’ve never needed all three juice boxes, but better to have more than I’ll need.
• I silenced my high alerts on my insulin pump. I don’t need a high alarm to interrupt my ride, since the exercise is going to lower my blood glucose anyway.

What I did during the ride

• I checked my CGM frequently to see how I was doing. I checked about every 15-20 minutes.
• I ate some candy when I saw a double down arrow trend.

What I did after the ride

• After the ride, I was hungry for a meal, and my blood glucose started trending up, as it often does after intense exercise. I tried to not over-correct, and I bolused a bit smaller amount for the food than normal, since intense exercise generally makes me more insulin sensitive.
• Later in the day, I ended up needing to treat hypoglycemia…. Apparently, my body didn’t need as much insulin as usual.

Showing off my Exercise Results

Here are a couple of screenshots from the Fitbit app which shows my current work out and previous bike rides.

Articles about Bike Riding with Type 1 Diabetes

LADA Diabetes is treated as Type 1, so these articles felt most relevant. I learned a lot from reading, as my personal experience is limited since I’m relatively new to this diabetes thing (compared to those with 10, 20, 40+ years of living with this!).

• The Thrill of the Ride: Bike Racing with Diabetes (DiaTribe). Former Team Novo Nordisk cyclist Ezra Ward-Packard shares how he manages his diabetes while endurance training, everything he’s learned over the last 12 years, and his advice for aspiring endurance athletes.
• Cycling – Using a pump, by John Richards. This page from RunSweet.com has a lot of advice from people with diabetes. Starts with John’s article and continues with content on cycling and managing diabetes from other writers.
• Seven Tips for Cycling With Diabetes (DiabetesSelfManagement.com) This was a really helpful article with practical info for people just getting started bike riding. Includes information about how choosing the right saddle is so very important. And the advice to take more glucose than you think you’ll need.
• Cycling and Type 1 Diabetes: how the pros manage (CyclingTips.com) Did you know that there was a pro team of cyclists who all have diabetes? Check out how the pros of Team Novo Nordisk (formerly Team Type 1) manage their diabetes.
• 6 Lessons From Cycling 10,000 Miles with Type 1 Diabetes This is a special guest post from BioLite Ambassador Annalisa van den Bergh. Annalisa is the founder of Miles of Portraits, a magazine and film series about the people she meets while cycling around the world.
• What Cycling Really, Really Far Taught Us About Our Type 1 Diabetes (BeyondType1)