The Insulin Timing Hack That Let Me Consume 300g of Carbs With Just 3 Units—What Every Diabetic Can Learn
Master insulin TIMING and VOLUME. Turn blood sugars from rollercoaster to a flat line.
I used to think that high and low blood sugars were inevitable during training.
This belief held me back for years. Every run or gym session was ruined by a sudden low or a sky-high hyperglycamia. If 2 years ago you had told me that I’d complete a 4 hours endurance workout with rock solid blood sugars, I would’ve laughed hard and told you to put down that bottle of Whiskey.
But things change.
I just completed a “brick session” (2-hour bike + 2-hour run) in preparation for my upcoming Ironman 70.3.
And guess what?
I maintained incredible blood sugar control throughout the entire 4-hour session — slamming down over 300g of carbs with only 3 units of insulin.
And I attribute this success to one key factor: precise timing of rapid insulin before exercise.
The Magic "Insulin Tail-End" Strategy Explained
You might have heard me talk about the “insulin tail-end” strategy before.
Here’s the core idea: most rapid insulin has a lifetime around 3 hours, so we can expect it to circulate around our system for three hours after injection. In the case of vigorous workouts (such as 4 hours of intense aerobic activity), having recent insulin on board means one thing and one thing only: a sentence to low blood sugars. So, to avoid this risk and still be able to consume carbs, I strategically give my insulin around 2-2.5 hours before the workout.
This creates a perfect, gentle overlap between:
insulin's final effect
the start of exercise
This is crucial to understand.
Physical activity boosts insulin sensitivity naturally, and it effectively "reactivates" the residual insulin, extending its effect to manage a massive amount of carbohydrates without risking lows or highs.
Let me break down what I did and why in details for you (follow along in the CGM graph below).
My Exact Pre-Workout Timeline (For Rock Solid Blood Sugars)
I woke up at 5:00 AM and immediately checked my blood sugars.
I knew my exact carb:insulin ratio from the day before, because I had been tracking it down to the decimals like a detective. Based on that, I could plan the appropriate insulin/carb strategy to start my workout with blood sugars around 150 mg/dL (and ideally keep them there). Around 6:00 AM, I ate my pre-workout meal (70g of carbs) and took my insulin.
Here's the critical part:
My carb-to-insulin ratio that morning was 10:1, meaning I would typically need 7 units for my meal. But knowing I was about to engage in 4 hours of high-intensity exercise, I took less than half my normal dose — just 3 units.
I ate slowly to avoid spikes from my snack, and monitored my blood sugars until go-time (8 AM). When I started the bike ride, I was at 174 mg/dL - slightly higher but perfect for a 4 hour long endurance work.
I had a solid nutrition plan during my performance:
90g of carbs per hour during the bike segment
50g of carbs per hour during the run
And this carefully timed insulin dose was the foundation for everything that followed.
Managing Massive Amounts Of Carbs During the Bike Portion
Remember: I started to ride at 170 mg/dL with residual insulin in my system.
The plan was to consuming carbs continuously to offset the drop in blood sugars and keep everything flat and stable. I had calculated everything: 2 sports drink bottles with maltodextrin + energy gels, amounting to exactly 90 grams of carbohydrates per hour. A ridiculous amount of sugar for someone living with T1 Diabetes.
Yet, my blood sugars remained remarkably stable.
Why? Because that residual insulin from 2.5 hours earlier was still doing its job.
Without it, I would have surely gotten above 300 in just a few minutes, dehydrated, with cramps and perhaps even DKA. Instead, I maintained my performance and my blood sugars on point without blood sugar dramas.
This is the hidden superpower of the tail-end strategy — which I’ve been using in my recent marathons and just keeps surprising me.
It allows you to fuel properly without requiring additional insulin doses during exercise (which can be extremely unpredictable and dangerous).
Transitioning to the Run (With A Few Panic Moments)
Came home from my bike ride at 170 mg/dL, laced my shoes up and went straight into a 2h run.
About 20-30 minutes into my run (after completing the bike portion), I noticed my CGM showing a downward trend — 156 mg/dL with an arrow pointing down. That was the extra insulin sensitivity starting to compound. This is where many endurance athletes panic (I did too many times in the past).
But I had anticipated this moment, and knew what to do.
I knew I needed to act quickly and proactively, so I consumed about 70g of carbs all at once to prevent further dropping. I also slowed down my pace to help my body digest carbohydrates more efficiently (instead of pumping blood to the working muscles in my running legs). This immediately stabilized my blood sugar around 160 mg/dL for the remainder of the run.
Then I only had to keep eating to keep my blood sugars up, so I sipped on my gels once every 10 minutes to offset the downward trend.
The lesson here?
Always be proactive rather than reactive with blood sugar management during (Especially during endurance activities). That single intervention prevented what could have been a session-ending low.
The Often-Overlooked Role of Basal Insulin
Another crucial element of my strategy was not reducing my basal insulin the day before the workout.
This goes against common advice, but maintaining my full dose provided essential background insulin control once my rapid insulin was about to wear off. After all, I could not hope that a 6AM bolus would keep up until 12PM!
I also strategically timed my long-acting insulin injection for optimal coverage.
I timed my Lantus injection the night before to peak during my workout the next day (Lantus typically peaks from around 10 hours after injection).
In other words, I created a nice synergy between properly timed basal insulin and the tail-end of my rapid bolus — the perfect environment for stable blood sugars throughout the entire session.
Why that Post-Workout Spike?
If you look on the right end of the graph, you’ll notice a spike right after finishing.
To be precise, my blood sugar began rising as soon as started cooling down.
Why? After 4 hours of training?
It took me months to figure this out — but I did eventually, with the help of my coach Matt Vande Vegte. And it is one truly fascinating insight: when you're exercising at high intensity, blood flow is directed toward working muscles and away from the digestive system. This temporarily slows glucose absorption.
But once you stop or slow down, digestion resumes at full speed, and all those carbs you've consumed start hitting your bloodstream at once.
That’s the reason behind that spike (after consuming 300g of carbs with minimal insulin).
All I did was taking a half-dose of insulin for my recovery meal (accounting for my increased insulin sensitivity) and watching my blood sugars stabilize around 120 mg/dL for hours afterward.
The Power of Mastering Insulin Timing
This session reinforced what I've been learning:
insulin timing is perhaps one of the most critical variables for endurance athletes with Type 1 Diabetes.
Getting both the timing AND volume right creates a foundation for success. If I had taken my normal 7 units before the workout (instead of 3), I would have been fighting dangerous lows throughout the entire session.
The ability to consume over 300g of carbs with minimal insulin while maintaining stable blood sugars wasn’t magic — it was the result of precise timing and strategic planning.
The Bottom Line
If you're a Type 1 diabetic athlete looking to tackle longer endurance events:
Experiment with the "insulin tail-end" strategy — bolus a few hours before starting your workout (around 2 hours works for me).
Consider reducing your pre-exercise insulin dose — I used less than half my normal amount that morning, to avoid lows.
Don't automatically reduce your basal insulin before big training sessions. It could be your greatest ally during longer sessions. Just don’t over do it…it’s still insulin in your body.
Time your long-acting insulin to peak during your workout.
Be prepared for possible post-exercise spikes, when your digestive system "catches up" on all the glucose you’ve consumed.
This approach completely transformed my ability to handle long training sessions, and it is helping me break through to the next level in my endurance journey — even with Type 1 Diabetes.
And that's the beautiful thing about this disease — once you figure out how to hack it, you discover capabilities you never thought possible.
Did it help?
❤️ Loved it. Leave a comment below and let me know your experience.
🥳I’m new here. Welcome! You can subscribe here.
👏 Helpful! You can refer it to a friend.