The Run Starts Before the Run: My Complete Pre-Run Protocol for Running with T1D (Part 1 of 12)

The Run Starts Before the Run: My Complete Pre-Run Protocol for Running with T1D (Part 1 of 12)

I have run 15 marathons. And before every single one, before every training run, every easy jog, every “I’ll just do a quick 3 miles” there is a process.

It starts long before I lace up.

This is Part 1 of a 12-part series breaking down everything that actually goes into running with Type 1 diabetes. Not the inspirational version. The real one. The one that lives in the hours before mile one even begins.

 Step 1: The CGM Check and Why the Number Is Only Half the Story

Before I touch my shoes, I check my Continuous Glucose Monitor (CGM)

But here’s what took me years to really understand: the number alone means almost nothing. What matters is the trend arrow, and the rate of change.

A blood sugar of 110 mg/dL sounds great. And it is if it’s flat or trending slightly upward. But 110 with a double-down arrow is a completely different situation. That means my sugar is dropping fast, and the moment I start running and my muscles start pulling glucose, I could be heading for a low mid-run with zero warning.

What I’m looking for before I head out

– Target range: roughly 130–180 mg/dL (higher end for longer runs)

– Trend arrow: flat or slightly rising = green light

– Dropping arrow: eat something, wait, recheck before going

– Rising fast: depending on how high, I may delay or adjust insulin first

Step 2: Basal Rate: The Adjustment Most People Don’t Know About

This is the one that changed everything for my long run management.

If you’re on an insulin pump, your basal rate — the background insulin dripping in all day — doesn’t turn off the moment you start running. Insulin that’s already been delivered is still active in your body, still working, still capable of dropping your blood sugar while your muscles are simultaneously pulling glucose out of your bloodstream.

The fix isn’t complicated, but the timing is everything.

Research supports reducing your basal rate by 50–80% starting 90 minutes before your run not when you lace up, not when you walk out the door. 90 minutes before. That lead time exists because reducing your basal doesn’t have an immediate effect. Insulin already delivered is still on board. You’re getting ahead of what’s coming, not reacting to what’s already happening.

For pump users with a sports mode or activity mode feature: this is exactly what it’s designed for. Set it. Use it. Just set it 90 minutes out or more and leave it on during your run. Sometimes depending on where my blood glucose is trending, I’ll turn off sports mode nearing the end of my run to try and head off the post run rise.

Some runners, depending on the workout, their sensitivity, and their numbers reduce basal even more aggressively or suspend the pump entirely for the duration of their run. Everybody is different. This is where logging your runs and your numbers over time becomes one of your most powerful tools.

My general approach:

– Easy recovery run: 50% basal reduction, set a minimum of 90 minutes before

– Long run or marathon training run: 70–80% reduction, set a minimum of 90 minutes before

– Race day: I treat this as its own protocol entirely (that’s a future post in this series)

Note: These are starting points based on research and my own experience — work with your care team to dial in what’s right for your body.

Step 3: Insulin on Board and the Pre-Run Meal Question

IOB: insulin on board. This is the variable that can quietly wreck a run if you’re not thinking about it.

Rapid-acting insulin stays active in your body for roughly 3–4 hours after a dose. So, if you ate, bolused, and then try to run two hours later, you have insulin still working, which combined with the glucose-lowering effect of exercise can send you crashing fast.

If you eat before a run, do NOT take a full bolus.

The research on this is clear. If you’re running within 2–3 hours of eating:

Easy 30-minute run: reduce your bolus by about 25%

Moderate 60-minute run: reduce your bolus by up to 75%

Long run or marathon training: some runners reduce pre-run meal bolus by 75% or more

You’re not skipping insulin. You’re scaling it to what your body is actually about to do with that food. The run itself is going to drive your blood sugar down — your bolus needs to account for that.

And here’s the part people don’t always think about: post-run meals need less insulin too. Exercise increases your insulin sensitivity for hours after you finish. Meals eaten in the window after a run especially after a long run may need 25–50% less insulin than usual. Correction doses right before, during, and immediately after a run should be reduced by 50–75%.

Write this stuff down. Every run. Your patterns will start to emerge.

Step 4: Gear Check And I Mean ON Your Body

Fast carbs have to be on you. Not in the car. Not in a bag at the trailhead. Not somewhere in your jacket. On your body, in a pocket you can reach without breaking stride.

I run with fruit snacks, gummy nerd clusters or a gel in an accessible pocket every single time. My CGM is secured with extra adhesive because sweat and sensor adhesive have a complicated relationship. My phone is charged because my CGM transmits to it. I carry ID on every run, no exceptions.

For longer runs I also carry:

– More carbs than I think I’ll need (I always need more than I think)

– Water, because dehydration makes blood sugar unpredictable

– An emergency contact who knows my route

Check Out What I Use To Run Here~

Step 5: The Mental Flip

This one doesn’t get written about enough, and I think it should.

Sometimes everything checks out — blood sugar in range, basal adjusted, gear loaded, insulin dialed back — and I still have to make a conscious decision to go. A deliberate choice that involves quieting a background anxiety that I think most T1D runners know intimately.

What if my sugar drops on mile 4 and I’m alone?

What if my CGM loses signal right when I need it?

What if I miscalculated?

Managing those thoughts, and going anyway, is a skill. It’s one I’ve been building for 15 marathons and I’m still building it. It doesn’t disappear. You just get better at working with it.

Running with T1D requires a kind of courage that has nothing to do with your pace or your mileage. It’s the courage to start — with imperfect numbers, with variables you can’t fully control, with a body that requires more negotiation than most training plans account for.

That courage is the foundation of everything else in this series.

Why This Series Exists

Training plans are written for predictable bodies. Mine isn’t predictable. Yours might not be either.

Over the next 11 parts, I’m breaking down every layer mid-run management, post-run recovery, race day protocols, the gear that makes this possible, nutrition strategy, the mental game, and everything in between.

Because you can run with T1D. You can run marathons with T1D. But you need a different playbook.

This is it.

Always work with your diabetes care team when adjusting insulin for exercise. Every T1D responds differently — these protocols are starting points, not prescriptions.

Have a pre-run protocol that works for you? Drop it in the comments — I want to know what your systems check looks like.