Exercise and T1D: Your Full Guide to Blood Sugar Friendly Workouts

Let’s Get Sweaty & Steady… Your Full Guide to Blood Sugar Friendly Workouts

Being diagnosed with type 1 diabetes was specifically hard for me, especially after 10 years of practicing as a competitive gymnast. I was used to feeling strong. Now when I exercised, I had to make sure I carbed up beforehand, had a Gatorade in my bag at all times and had to mentally prepare myself for the low blood sugar that was bound to happen.

My endocrinologist was less than helpful in all of this. Whenever I asked for advice I was met with “make sure your blood sugar is over 150 mg/dl (8.3 mmol) and bring a juice with you just in case”. Naturally I felt defeated. I just wanted to do one healthy thing for my body and instead I was consistently ending up in the locker room with a pack of Skittles. Chances are if you’re reading this, you’ve been there too.

What I was never educated on were all of the different factors that play into our activity blood sugars. Instead of learning how to manipulate the different variables, I was always taught to manipulate the blood sugar. In turn, I felt frustrated, annoyed and my blood sugars were sent on an even bigger rollercoaster. The opposite of what I wanted. Now, after nine years and getting my personal training certification, I’m finally able to walk into every gym session confidently (and most importantly, interruption-free).

Inside this blog post, I’m going to take you through the different variables to consider in your workout and how they impact your blood sugar outcomes.

Variable #1: Considerably the Most Important – Intensity

Chances are, if you have found resources online about exercising with diabetes you have come across the misconception that weight lifting leads to high blood sugars and cardio leads to low blood sugars. And so when you go to the gym and start lifting weights, you notice your blood sugar drop. What the heck, right?

The key player being left out of this generalized statement is intensity ie. how hard your body is working during that activity. You can weight lift at low intensity and you can weight lift at high intensity. You can do cardio at low intensity and you can do cardio at high intensity. Each one will drive different results in your blood sugars – so let’s break it down.

There are three main ways to measure intensity:

#1: Your Heart Rate

This is where your Apple Watch or FitBit will come in handy. Using your heart rate measurement, you can gauge at what demand your body is working at. This requires some math though, so let’s go through it together.

Everyone has an estimated maximum heart rate. This is an estimated to how high your heart rate can go before you physically cannot complete the rest of the exercise. Keep in mind, this number will change depending on if you take Beta Blockers or have any other conditions. But generally, this number is measured by taking the number 220 minus your age.

Estimated Maximum Heart Rate = 220 – your age.

Example: I’m 28 so my estimated maximum HR is 220 – 28 = 192.

This will be the number you’ll compare your working heart rate to.

To find the percentage of maximum heart rate your body is working, you’ll need to divide your working heart rate by your max HR and multiply it by 100%.

Example: If my working heart rate is 160 bpm, I will divide that by 192.

160 / 192 = .833

.833 * 100% = 83% of my maximum heart rate.

Moderate intensity exercise will be between 50-70% of your maximum heart rate, where vigorous intensity will be 70-85% of your maximum heart rate. Typically for people with diabetes, we will see a lowering or stabilization in our blood sugars with moderate intensity and an increase in our blood sugars during vigorous intensity. However, it’s important to find your own personal trends.

#2: The Talk Test

If you don’t have means to measure your heart rate, don’t worry – there are other tools to be able to measure the intensity you’re working at. This tool is called the Talk Test is a tool to measure general intensity. Doing this is easy, you simply see how well you can have a conversation or even say your ABC’s!

Think about when you’re taking a walk with a friend. Chances are, it’s really easy for you to have a conversation without having to breath heavily. This means you’re moving at low or moderate intensity. On the opposite end, when you’re doing high intensity movement like weight lifting, CrossFit, or sprints (just to name a few), it’s rare that you’ll be able to get through your ABC’s without huffing and puffing. This means you’re moving at more vigorous intensity.

#3: RPE – Rate of Perceived Exertion

This tool is the easiest to use, but the most inaccurate (or up to interpretation). Perceived exertion is how hard you feel like your body is working and is generally rated on a scale of 1-10. You can use the following chart from Marathon Handbook to gauge the intensity of your workout.

Generally speaking, the higher the intensity, the more chance for a blood sugar spike. The lower the intensity, the more chance for a lower blood sugar to happen.

Variable #2: Insulin on Board

Insulin on board (IOB) can help you or hurt you during your workout depending on the intensity that your body is moving. There are a few things to consider when looking into IOB.

• Insulin can last in your body for 4-5 hours and peak around 1-2 hours (depending on the insulin you use).
• When we move our body, insulin works more efficiently. So you may see a bigger drop, quicker.

When IOB may hurt you:

• When you are doing lower intensity exercise
• When your last dose was 0-2 hours before your workout

When IOB may help you:

• When you are doing a higher intensity workout
• When your last dose was 2+ hours before your workout

Some things that may help offset insulin on board are temporary basals or additional carbohydrates.

Again, learning your own body’s patterns and understanding the insulin you use is key here.

Variable #3: Timing of Your Last Meal

There are two key reasons why looking into the timing of your last meal is important. #1 because it typically correlates with your last dose and #2 because exercise slows down digestion.

How it affects your workout:

When your last snack or meal is too close to your workout, you may experience a blood sugar spike afterwards. Keep in mind that high protein or high fat meals can delay digestion even more. Some people experience a low blood sugar during their workout because of the active insulin and a spike after the workout due to delayed digestion.

The key? If you’re experiencing post workout high blood sugars, it may be helpful to give your body adequate time to digest before exercising and prioritizing hydration.

Tying it All Together..

While there are more variables at play, these three are with-out-a-doubt the key ones to consider first if you’re troubleshooting your workout blood sugars. During this process, your best friend will be the Keeping it 100 Diabetes Journal, which gives you all of the tracking sheets needed to reflect on all of the key variables and nail down your workout strategy once and for all. Grab yours here:

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