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Reducing 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 which a 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…
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 information 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:
total kcal from fat and protein
= 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 Diabetes Canada. 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.
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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