Total Insulin vs. Timing of Insulin: Understanding the Difference in T1D Management

When you're diagnosed with type 1 diabetes, you quickly learn there are two major insulin-related keys to keeping your blood sugar in range:

How much insulin you're taking (Total Insulin)
When you're taking it (Timing of Insulin)
Both matter. A lot. Let's break it down in a way that helps you troubleshoot blood sugar swings with more clarity and confidence.

What Is Total Insulin?

Your total insulin includes all the insulin your body gets in a day, whether it's through a pump or injections. This includes:

Basal insulin: Your background insulin, working 24/7 to manage blood sugar between meals and overnight
Bolus insulin: The insulin you take for food or to correct high blood sugar

Why Total Insulin Matters
If your total insulin is too much, you'll experience frequent lows.
If your total insulin is too little, you may stay high even after correcting or eating.

👉 Think of it like this: if your basal dose is off, your blood sugar will drift high or low even without food.
If your bolus dose is off, you'll notice bigger swings after meals.

What Is Insulin Timing?

Timing is about when you take your insulin-especially bolus insulin-relative to meals or activity.

Insulin doesn't work instantly. It takes time to start lowering blood sugar. If you mistime it, things can go sideways:

Spike right after eating? You may need to take insulin earlier (prebolus).
Go low right after eating? You might need to take insulin later, with or after the meal.

The Power of the Prebolus
Prebolusing (taking insulin 10-20 minutes before eating) helps match insulin action with food digestion. But this window can vary depending on:

The type of food
Your insulin type
Your insulin sensitivity
Time of day
Activity level

How to Troubleshoot Highs and Lows

When blood sugars go off-track, ask yourself:
"Is this a total insulin problem, or a timing problem?"

Here's how to tell ⬇️ 

If You're Going LOW

⏰ Timing Problem
Insulin kicked in before your food did.
Example: You prebolused, then your meal was delayed.
Fix: Take insulin closer to eating or even after starting your meal for slower-digesting foods.
💉 Total Insulin Problem
You took too much insulin for the amount of food.
Blood sugar is okay for a bit, then crashes.
Fix: Reevaluate your carb ratio or eat a bit more next time.

If You're Going HIGH

⏰ Timing Problem
Big spike right after a meal.
Insulin started working too late to prevent the spike.
Fix: Try bolusing earlier next time (prebolus 10-20 minutes before eating).

💉 Total Insulin Problem
You go high and stay high, even with a correction.
This may mean your:
Carb count was off
Insulin-to-carb ratio needs adjusting
Correction factor isn't strong enough
Fix: Review your math, food labels, or talk with your provider about dose adjustments.

The Basal Clue

If you're waking up high or consistently dropping low without eating

🎯 That's likely a basal insulin issue, not bolus or timing.

Test your basal by:

Fasting for a few hours and watching your CGM
Doing a basal test (under guidance from your care team)
Tracking patterns across multiple days

Trends Over Time > Single Numbers

One number doesn't tell the whole story.

Instead, look at:

Time of day trends (e.g. do you spike every breakfast?)
Activity patterns (e.g. do you crash after strength training?)
Food patterns (e.g. does pizza always leave you high 4 hours later?)
Over time, you'll start seeing cause-effect patterns and feel more confident making adjustments.

Quick Troubleshooting Cheat Sheet

If you're going LOW within 1-2 hours of eating:
Your insulin is hitting before your food does. Try shortening your prebolus time, or bolus right when you start eating instead of before.

If you're going LOW 3+ hours after eating:
You may have too much insulin on board. Try reducing your meal dose, or check if your basal rates are too high.

If you're going HIGH right after eating (within 1-2 hours):
Your insulin isn't getting there fast enough. Try prebolusing earlier, or you may need a stronger carb ratio.

If you're going HIGH hours later (3-5 hours after eating):
This is often a fat/protein spike, not a carb issue. Check out the HFHP bolusing strategy.

If you're always running HIGH or LOW regardless of meals:
This is usually a basal issue, not a meal bolusing issue. Check your basal rates (pump) or long-acting insulin dose.

Final Tips

Don't blame yourself for every high or low. Diabetes management is a mix of art and science.
Be intentional, not perfect. Perfection isn't the goal-understanding your body is.
Track trends, not just numbers.
Ask for help if needed. Whether it's from a coach, educator, or provider-support makes a difference.
Take Action

Choose one area to focus on this week: Total insulin or timing.
Watch what happens before and after meals or corrections.
Make one small adjustment-and document the result.
Celebrate progress, not perfection.

The more you understand your insulin patterns, the more you take back control.

You've got this.

Stay fun,

Madi Cheever, MPH, RD, LDN, CHES
Type One Type Fun

️DISCLAIMER: although I am a healthcare professional, this post is not intended to be medical advice. This is simply me sharing some of what I know, but your body may not respond in this way so please make sure you are chatting with your diabetes educator and/or doctor first ️ or bring me onto your care team 😘