Diabetes and Fitness: A Practical 2-Part Guide

Part 1: Mastering Diabetes and Fitness – A Practical Guide

Starting Strong: Why Fitness and Diabetes Go Hand in Hand

Managing type 1 diabetes has been a wild ride—full of lessons, setbacks, and aha moments. Back when I was carrying a lot more weight, everything about my diabetes felt harder. My insulin doses were sky-high—both the long-acting kind and the fast-acting stuff—and my lack of exercise wasn’t doing me any favors. It was like I was stuck in this loop: the more weight I carried, the more insulin I needed, and the more insulin I took, the harder it was to manage my blood sugar.

Here’s the thing—having more body fat does make you more insulin resistant. That’s just science. No matter how “healthy” someone might seem or feel, the more fat you’re carrying, the harder your body has to work. Movements like fat liberation, led by voices like Virgie Tovar, often focus on self-acceptance (which is important!), but they tend to gloss over the cold, hard truth: adiposity impacts your health whether you feel it today or not. If you need proof, just check out the study I’ve linked here—it’s one of many that break this down.

When I finally decided to make a change and start exercising, I quickly realized how much I didn’t know. Turns out, diabetes and fitness don’t always play nicely together. I found myself needing insulin before workouts (yeah, who knew?), adjusting doses based on whether I was running long distances, smashing through a short burst of cardio, or lifting weights. It was like learning a new language: one part trial-and-error, two parts “let’s hope this works.”

And let me tell you, it wasn’t all smooth sailing. I’ve had workouts where I crashed halfway through or shot up to the high 20s because I didn’t plan things out. But every misstep taught me something. Eventually, I figured out what worked for me—how to prep for workouts, how to keep my blood sugar stable, and how to bounce back when things didn’t go as planned.

That’s why I’m here, writing this blog. If you’re diabetic and trying to stay active, I want to help you avoid the bumps I hit along the way. Consider this your cheat sheet—a guide to navigating fitness with diabetes so you can focus on crushing your goals without all the guesswork. Let’s get started!

Understanding the Challenges of Diabetes and Exercise

Exercise-Induced Blood Sugar Spikes

One of the most shocking—and honestly frustrating—things I learned early on in my fitness journey was that exercising could make my blood sugar skyrocket before the dreaded crash. Up until then, doctors had only warned me to be cautious with exercise because it could send me into glycemic shock (low blood sugar). At the same time, they kept emphasizing that I needed to exercise to lose weight. Talk about mixed signals!

You can imagine my confusion (and exhaustion) when, after my first martial arts class, my blood sugar shot up from a steady 8 or 9 mmol/L to a staggering 22 mmol/L. No one had prepared me for this, and I felt completely blindsided.

Here’s what I later learned: during exercise, your body releases cortisol—a stress hormone that triggers your liver to break down glycogen (stored glucose) and flood it into your bloodstream. This is your body’s way of making sure your muscles have the energy to keep performing. But as a diabetic, without the right insulin balance, this glucose release can send your blood sugar soaring.

Back then, I didn’t know this, so my first instinct after seeing my post-workout numbers was to do what I always did when my sugar was high—take insulin. What I didn’t realize was that this spike was temporary, and once my body burned through the extra glucose, I was headed for a sudden and severe low.

And that’s where things get tricky—the crash.

Risk of Lows Post-Workout

If the post-workout spike wasn’t challenging enough, there’s another curveball that exercise throws at diabetics: delayed hypoglycemia. After your workout, your muscles aren’t done working—they continue to replenish glycogen (stored glucose) from your bloodstream for hours. This natural recovery process, combined with increased insulin sensitivity, can cause blood sugar to drop an unexpectedly long time after you've left the gym.

Studies have shown that intensive glucose control increases the risk of hypoglycemia, especially in individuals using insulin. The body’s counter-regulatory response—designed to prevent blood sugar from dropping too low—can become impaired over time, making diabetics more vulnerable to delayed hypoglycemia without proper management.

For me, the lows would often hit out of nowhere. I’d feel completely fine after a workout, only to be shaky and lightheaded hours later. It was frustrating because I didn’t understand what was happening or how to prevent it. Through trial and error, I learned some crucial steps to prepare for these crashes, rather than scrambling to fix them when they hit. Here's what I learned:

How to Avoid Delayed Hypoglycemia

Monitor Blood Sugar Before, During (if possible), and After Workouts

• Start by checking your blood sugar before exercising. Aim for a safe range—neither too low nor too high. If you’re below 5.5 mmol/L, have a quick snack with fast-acting carbs before you begin.

• During long or intense workouts, check your levels periodically to catch any sudden changes. You will either get used to your body and how it reacts as I did, or after the first month or so of training, you will learn how your body responds. Having glucose tablets or a sports drink nearby can be a lifesaver.

• After the workout, keep an eye on your blood sugar for the next 4–8 hours. This is when delayed lows are most likely to happen.

  
  

Refuel Post-Workout

• Eat a balanced post-workout meal or snack that includes both carbs and protein. The carbs help restore glycogen, while protein aids muscle recovery. I found that having a banana with peanut butter or a small protein shake works very well—and tastes amazing post-workout!

  
  

Adjust Your Insulin

• Speak to your healthcare provider about adjusting your insulin doses around workouts. For example, you might reduce your basal insulin slightly on workout days or take less bolus insulin with your post-workout meal—basal being your long-acting background insulin and bolus the fast-acting one for meals and corrections.

• Keep in mind that insulin sensitivity increases after exercise, so your usual will probably need some tweaking.

  
  

Learn Your Patterns

• Everyone’s body reacts differently to exercise, so take note of what works for you. Use a continuous glucose monitor (CGM) or log your workouts and blood sugar trends to identify patterns and adjust accordingly.

  
  

Next Steps

Understanding how exercise affects blood sugar is just the first step. Now that we’ve covered the science behind blood sugar fluctuations, it’s time to move on to optimizing your workouts, planning your nutrition, and making fitness sustainable.

📢 Stay tuned for Part 2, where I’ll dive into workout planning, overcoming mental barriers, and building long-term success!

Let’s Keep the Conversation Going

If this blog resonated with you, I’d love to hear from you! Follow me here for more fitness and diabetes content, connect with me on social media, and share your own journey. Let’s build a community that supports and uplifts each other—because no one should have to figure this out alone.

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