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Prevent Post-Meal Spikes: Fat and Protein

Michelle MacPhee, D-Mom

In addition to the well-known blood-sugar-raising effect of carbohydrates, we now know that protein and fat also impact blood glucose, and that this effect can be significant.

So what can we do to avoid the post-meal spikes associated with the intake of fat and protein? How much additional insulin may be needed? And how/when do we deliver the insulin to match the late effect of fat?


Background reading for this article:
How Fat and Protein Affect Blood Glucose

A Method for Dealing with Fat and Protein

The Warsaw School Program for Dosing Mealtime Insulin proposes one approach, widely used by patients with diabetes in Poland and Germany. In addition to bolusing for carbohydrates in much the same way that we do here in Canada (by counting carbs and using a Normal Bolus to deliver insulin according to an individualized I:C ratio), the Warsaw School advocates a separate bolus for protein and fat, given as an extended bolus, the duration of which is determined by the amount of protein and fat in the meal. The amount of protein and fat in the meal is expressed in “Fat-Protein Units” (FPU). One FPU is equivalent to 100 kcal of fat or protein, and has a blood-glucose-raising effect equivalent to 10g of carbs. From those basics, the Warsaw School approach outlines a systematic process for calculating the additional insulin that may be needed to cover the fat and protein content of a meal, in whicha low-protein/low-fat meal would call for little to no extra insulin, while proportionally more insulin would be required for a high fat and/or high-protein meal. Keep in mind that, despite what some consider controversy on the effect of protein on BG, as discussed above, the effect of protein IS included in this approach.

After giving a normal bolus to cover the carbohydrates (26g in the example below), the extra insulin (dose and duration) to cover fat and protein is calculated using Fat-Protein Units (FPU’s) as in the following example.

(Stick with me! It may look daunting but makes more sense with an example, given in blue below… also read through to the end to learn about the adaptations I use to reduce the very real risk of lows!)

For simplicity, we will consider a single fat- and protein-containing food item, a Klondike® Kandy Bar™ ice cream treat…

The Calculation

1. Identify how much fat and how much protein the food contains.

We start by finding out the number of grams of fat and the number of grams of protein. We can get this infirmation from a nutrition facts label, or by using a nutritional scale, or by accessing a food database (app, book, or website, for example). If your meal includes more than one significant source of fat and/or protein, you can add up the fat and protein values from each of the different foods, and then work with those totals according to the same process.

Example: In one Kandy Bar, there are 3g of protein and 14g of fat.

2. Convert into units of energy.

Multiply the grams of protein by a factor of 4, and the grams of fat by a factor of 9, to determine the amount of energy (in kcal) contributed by each. Why 4 and 9? That’s simply the mathematical relationship between grams of fat (or protein) and kilo-calories:

kcal from protein = Protein (in grams) x 4 kcal/g
Ex: 3g of protein x 4 = 12 kcal from protein

kcal from fat = Fat (in grams) x 9 kcal/g
Ex: 14g of fat x 9 = 126 kcal from fat

3. Calculate the Total Calories.

Add these two together to get the TOTAL calories from protein and fat combined.

TOTAL kcal from Fat and Protein = kcal from protein + kcal from fat
Ex. 12 kcal from protein + 126 kcal from fat= 138 total kcal (from fat & protein)

4. Calculate Fat-Protein Units.

Calculate the number of FPU’s by dividing the total kcal by 100kcal per FPU:

FPU’s =
total kcal from fat and protein
100 kcal/FPU

138 kcal
100 kcal/FPU

=1.38 FPU’s
= 1 FPU (rounded to nearest full unit)

5. How long is the extended bolus?

This number of FPU’s tells you how long to extend the bolus.

To determine this duration of the extended bolus, check the following chart:

for 1 FPU, program the extended bolus over 3 hours
for 2 FPUs, program the extended bolus over 4 hours
for 3 FPUs, program the extended bolus over 5 hours
for 4 FPUs, program the extended bolus over 8 hours

Ex: For one Kandy Bar (which contains 1 FPU), we will extend the bolus over 3 hours.

6. How much extra insulin is needed?

To determine the amount of insulin to deliver in that extended bolus, multiply by *10 (‘carbs’ per FPU equivalent) and then divide by your insulin-to-carb ratio for that time of day:

FPUs x 10g ‘Carbs’ per FPU = ____ g ‘Carbs’ equivalent ÷ I:C ratio
= ____ units of insulin

1.38 FPUs x 10g ‘Carbs’ per FPU = 13.8g ‘Carbs’ equivalent ÷ 15
(1:15 is my son’s supper ratio; yours will likely be different!)

= .92 U of insulin in the Extended Bolus
= .90 U of insulin (rounded to the nearest 0.05U)
(my son’s pump delivers bolus insulin in increments of .05U)

To summarize, in this example, to cover the fat and protein when my son has a Kandy Bar after supper, I would deliver 0.9U of insulin extended over 3 hours.

* This number “10” in the formula can be changed to decrease the amount of extra insulin given to cover fat, if needed. See Tips from the Trenches below.


… it’s not quite that straightforward.

The first problem is that patients in the population in which the above method is commonly used have what many would consider an unacceptably high rate of hypoglycemia (low blood sugar). So it may be risky to follow this method exactly as outlined above.

The second point to note is that this process is not currently considered best practice within the Clinical Practice Guidelines set out by the Canadian Diabetes Association. So, according to Canadian health care professionals, it may be risky to follow this method as outlined above.

The third caveat, as always, is that “Your Diabetes May Vary”! There are individual differences in how different bodies process carbs, fats and protein, differences in portion sizes, food items, amount of exercise already completed and planned, hormones, body types, stress levels, illness, etc. So it is wise to use the general principles outlined here within the context of your own situation, and CONSULT YOUR DIABETES HEALTH CARE TEAM if you would like to implement these principles within your own/your child’s blood glucose management program.

Tips from the Trenches

From Michelle:


When I used the FPU concept exactly as outlined above to deal with high fat meals such as chicken nuggets and fries, ice cream, or pizza, my son’s BG went low (sometimes very low!) every time. So I adapted the Warsaw School process to reduce the amount of insulin. First, because Gary Scheiner talks about the fact that protein has little effect on BG when consumed with carbs, and because my son almost always has carbs when he eats protein, I dropped the Protein portion of this process entirely. I calculate the amount of Fat Units, and use that alone to determine the amount and duration of the extended bolus.

In addition, I play with the amount of ‘Carbs’ per FPU, given above as 10; usually I multiply the FPU’s instead by 8 (which further reduces the insulin dose).

For example, using the same Kandy Bar example above, after giving a normal bolus for carbs:
1. I start with the number of grams of fat only: 14g of fat in one Kandy Bar
2. I multiply the grams of fat by a factor of 9, to determine the amount of energy (in kcal) contributed by fat.
Fat (in grams) x 9 kcal/g = ____ kcal from fat
14g of fat x 9 kcal/g = 126

3. (I skip the protein step as outlined above in #2 example calculation – the total kcal is equal to the total grams of fat alone, since I don’t include protein.)

4. Calculate the number of FPU’s by dividing the total kcal by 100 kcal per FPU:

total kcal from fat = ____ FPU’s
100 kcal/FPU

126 kcal ÷ 100 kcal/FPU

=1.26 FPU’s
=1 FPU (rounded to nearest full unit)

5. According to the same chart above, I determine the duration of the extended bolus:

Ex: For one Kandy Bar, I would extend the bolus over 3 hours. (No change from the previous example.)

6. To determine the amount of insulin to deliver in that extended bolus, I multiply by 8 (instead of 10) and divide by the I:C for that time of day:

FPUs x8g ‘Carbs’ per FPU = ____ g ‘Carbs’ equivalent ÷ I:C ratio = ____ units of insulin

Ex: 1.26FPUs x 8g ‘Carbs’ per FPU = 10.1g ‘Carbs’ equivalent ÷ 15 (my son’s supper ratio)
= .67 U of insulin in the Extended Bolus
= .65 U of insulin (rounded to the nearest 0.05U)

To summarize, using the ADAPTED Warsaw School approach in this example, when my son has a Kandy Bar after supper I would deliver 0.65U of insulin extended over 3 hours.

Compared to 0.9U in the first example above, this adaptation presents a more conservative version of the Warsaw School program; one that we have found works GREAT in most cases for our son (check out some comparative BG data from our family’s experiments with FPU). We are still conscious of the risk of lows and check his BG often after using this formula; we find that around the 4-6 hour mark is when his BG may dip too low, so clearly we still have some tweaking to do, perhaps in terms of the duration of the extended bolus. We have had to bring in a low treatment at this point on more than one occasion, so I caution you to be vigilant with checking your child’s BG, especially before you have a good idea of the effect of this approach on his/her individual body. But that said, given that we are willing to be vigilant, we have found this approach to be a huge benefit to our family!

Tips from the Trenches

From Michelle:

At first I found this calculation to be cumbersome, and if I didn’t happen to have my FPU Worksheet with me when we wanted to get ice cream on an outing, then I was left with the same “by guess and by golly” approach that I had used before I learned about this concept. So I condensed the calculations (individualized for our son’s needs) into fewer steps and stored the shortened form on my phone for easy access on the go. Here is how I condensed the formula into fewer steps:

(Remember that this abridged form takes into account only fat – not protein – since this is what works for our son. You may need to come up with your own short hand to accurately reflect your child’s individual needs.)

grams of Fat x .09 = ____ FPU’s
(This number tells me the duration of the extended bolus.)
14 x .09 = 1.26 –> extend bolus for 3 hours

Then to calculate the insulin dose:

FPU’s x 8g ‘Carbs’ per FPU ÷ I:C ratio (which is 1:15 for most of the day)
= FPU’s x 8 ÷ 15 = ____ U
1.26 x 8 ÷ 15 = .67U, rounded to .65U

All I have to remember on the go is: x .09, x 8, ÷ I:C

Tips from the Trenches

From Danielle:
My son responds differently than Michelle’s when it comes to fat digestion! What I have found with Paul (after many years of trial and error) is that fat doesn’t seem to fully affect him until at least 6 hours after he eats it AND when I tried this approach as outlined above, his BG tanked at the 4 hour mark, so he needs insulin up front only for the carbs (needs the extra insulin to cover fat much later). I find the “pizza solution” to work better for him but it sure isn’t a spelled-out approach (like the above example). I still need to experiment more with possibly using a modified FPU approach. I would try using the amount of carbs and time guidelines found above (using the Fat Protein Unit calculations) and use it instead of a temporary basal rate increase 6 hours later in order to have a more mathematical approach.

And One Last Tip from the Trenches

From Michelle:
I have asked myself often, “What counts as ‘high fat’?” and though I still can’t answer that question in a precise way, we have found in our family that we don’t need to use this method for meals below 10g of total fat. That threshold may be higher or lower for other people with type one diabetes.

To peek at some actual blood glucose results using various approaches to dealing with fat and protein:
High-Fat Foods: A Case Study (Using Fat-Protein Units to Reduce Post-Meal Spikes)

We gratefully acknowledge the information provided by Lorraine Anderson (RD, CDE, Senior Clinical Manager, Animas Canada) and Shannon Cassar (RN, CDE, Alberta Children’s Hospital Diabetes Clinic), which served as the basis for this article. Without you, we might never had experienced this diabetes management revolution! Thank you!

The above information was reviewed for content accuracy by Lorraine Anderson, RD, CDE.

This material has been developed from sources that we believe are accurate, however, as the field of medicine (in particular as it applies to diabetes) is rapidly evolving, the information should not be relied upon, as it is designed for informational purposes only. It should not be used in place of medical advice, instruction and/or treatment. If you have specific questions, please consult your doctor or appropriate health care professional.

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