Calculating the ‘fat-protein’ math for type-1 diabetes

Show of hands, who here has ever calculated a bolus dose of insulin for high protein and, or high fat meals?

Up until yesterday, never have I ever.

You all, I eat a lot of the same meals and I’ve had T1D for many years. As such, I’ve managed (through great amounts of trial and error) to figure out various strategies for high fat meals, such as pizza and lasagna, that have worked quite well for me.

Until recently 🙁

Salmon: calculating mealtime insulin dose using fat-protein units

The Salmon Challenge

My blood sugars have seriously revolted against all dinners containing salmon.


How is this possible?

I eat salmon consistently at least once a week, sometimes twice a week.

Salmon used to be one of my go-to dinners prior to a long run the following morning.

I have never, or very rarely, had issues with salmon impacting my blood sugars.

Until about 3 months ago.

I started noticing my blood sugars steadily creeping up over the course of 2-6 hours following grilled salmon.

Initially, I thought the high blood sugars were something environmental.

It was just so out of the blue, I didn’t think it could possibly be the food.

But then it kept happening.

Patterns were formed.

It had to be the food.

I blamed the Greek salad that we usually accompany our salmon with.

It couldn’t possibly be the salmon, I thought.

I switched the Greek salad out for tossed salad.

The highs continued.

Bloody freaking hell, it was the salmon.

There was no way I was going to stop eating salmon – not even for optimal blood sugar management.

There had to be another way.

Bolusing Fat-Protein Units: The Math

Yes folks, there is another way.

Calculating bolus doses for fat-protein units (FPU).

Have you done it?

I did yesterday, and it worked brilliantly!

Here’s how it works:

In general, 1 FPU = 100 kcal and 10 grams carbs

First, you figure out how many ounces of salmon you have.

You can do this either by food scale or by guestimating. Generally speaking, approximately 3oz of salmon will fit into the palm of your hands and be the thickness of a deck of cards.

Then you figure out how many grams of protein, and how many grams of fat are in that serving.

Next, you’re going to calculate the calories from the protein and the calories from the fat.

Keeping in mind that 1 gram of protein = 4 kcal, and that 1 gram of fat = 9 kcal.

So let’s do the math shall we?

I had a 5 oz piece of salmon, and there’s approximately 18g of fat and 28g of protein in that portion.

Protein Math28 g x 4 kcal/g = 112 kcal from protein

Fat Math18 g x 9 kcal/g = 162 kcal from fat

FPU Math = 112 kcal + 162 kcal = 274 kcal = 2.75FPU = ~27g carbs additional (Remember: 1 FPU = 100 kcal / 10g carbs)

So now what?

The recommendation is to take your meal bolus based on the actual carbs for that meal prior to eating. Then, spread the FPU carbs over an extended period using a dual wave or extended bolus, per the following:

  • 1 FPU = extend over 3 hours
  • 2 FPU = extend over 4 hours
  • 3 FPU = extend over 5 hours
  • >3 FPU = extend over 8 hours

For my salmon, I rounded up to 3 FPU and extended the 27g over 5 hours. And my BG lines were beautifully level – no peaks, no valleys.

Cue the hallelujah! Salmon eating will continue 🙂

3 thoughts on “Calculating the ‘fat-protein’ math for type-1 diabetes”

  1. Hey there, great post! I love this, I think it’s an important and fantastic aspect of maintaining one’s blood sugars. I’ve noticed some “unexplainable highs” while eating salmon and other lean proteins that I would have otherwise assumed were carb-free. I was wondering if you could provide some insight into how I could incorporate this information if I use SmartGuard on my pump, which doesn’t allow for delayed bolusing such as dual of square wave. Any thoughts?

    1. Thanks Shawn!

      I don’t use SmartGuard myself and I’m not overly familiar with it. Can you program multiple basal programs? That might be one way around it – although, it would be pretty cumbersome.

      1. Yes, I believe you can program several different basal rates for each program as well. You lose square and dual bolus by using SmartGuard, which is also a pain.

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