π Warsaw Method (FPU) Calculator
Dosing the part of the meal carbs don't cover.
Fat-protein units
For informational purposes only, not medical advice.
The Warsaw Method converts a meal's fat and protein into fat-protein units: 1 FPU equals 100 kcal from fat plus protein, and each FPU acts like roughly 10 grams of carbohydrate for insulin dosing. A meal with 20 g of fat and 30 g of protein carries 300 kcal from the two, which is 3.0 FPU, a 30 g carb equivalent delivered as an extended bolus over about 5 hours. Developed by Pankowska's group in Poland and studied in children with type 1 diabetes on pumps, it doses the slow glucose rise that carb counting misses.
Fat and protein raise blood sugar late, hours after the meal, through slow digestion and gluconeogenesis. Carb-only boluses cover the first wave and leave the second, which is why pizza defeats even careful counters. The Warsaw Method splits the bolus: standard for the carbs now, extended for the fat and protein later.
How to Use This Calculator
Enter the meal's fat and protein in grams from the label or a food database. Optionally add your insulin-to-carb ratio to see the illustrative extended dose. Then take every number to your diabetes team before changing pump settings.
Enter fat and protein grams for the meal.
Read the FPU count, the carb equivalent, and the suggested extended-bolus window.
Optionally enter your insulin-to-carb ratio for an illustrative unit estimate, then confirm the real settings with your endocrinologist or educator.
The FPU Math
Fat yields 9 kcal per gram and protein 4, the standard Atwater values. Dividing their combined energy by 100 gives FPUs; multiplying FPUs by 10 translates them into the carb language pump ratios speak. The bolus windows lengthen with FPU count because bigger fat loads digest slower, a relationship the Polish studies mapped empirically.
In practice the meal bolus becomes dual-wave: the carb portion up front, the FPU portion spread across the window. Pump users program this as a combination bolus; people on injections cannot easily replicate the extended part, which is why the method is pump-specific.
Worked Example
A burger meal: 20 g fat, 30 g protein. Fat energy is 180 kcal, protein 120, total 300, divided by 100 gives 3.0 FPU. Times 10, the carb equivalent is 30 g. Three FPU maps to an extended window of about 5 hours.
With an insulin-to-carb ratio of 1:10, the extended portion illustrates at 3.0 units over 5 hours, on top of whatever the meal's actual carbohydrates need up front. The clinical studies showed this dual approach flattened the late post-meal spike that carb-only dosing left behind.
Reading Your Result
| FPU | Meaning |
|---|---|
| Under 1 | Small fat-protein load. Standard carb bolus usually suffices. |
| 1 to 2 | Moderate. Consider a 3-4 hour extended bolus per your team's guidance. |
| 3 or more | Large. The classic pizza scenario; extended bolus over 5-8 hours. |
My take: the method shines for predictable high-fat meals and matters less for lean ones. Do not chase precision on mixed home cooking; the FPU is an estimate, and diabetes teams tune the real ratios from glucose logs, not from arithmetic alone.
Limits and Safety
This is educational math, not dosing advice. Insulin dosing is individualized and mistakes cause hypoglycemia, which can be dangerous fast. The method was studied mainly in type 1 diabetes on pumps; it does not apply to type 2 on oral agents the same way. Gastroparesis, illness, and alcohol all change fat digestion timing. Every change to bolus strategy goes through your diabetes team first, no exceptions.
Related Tools
Diabetes math continues with the diabetes risk calculator, weight context comes from the BMI calculator, and meal energy from the macro calculator.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the Warsaw Method?
An insulin-dosing approach for type 1 diabetes on pumps that accounts for fat and protein using fat-protein units (FPUs). Developed by Pankowska and colleagues in Poland, it adds an extended bolus for the slow glucose rise that carbohydrate counting misses.
What is an FPU?
A fat-protein unit: 100 kcal of combined fat and protein energy. Fat provides 9 kcal/g and protein 4 kcal/g, so (fat x 9 + protein x 4) / 100 gives the FPU count. Each FPU equals roughly 10 g of carbohydrate equivalent for dosing.
How long should the extended bolus run?
By the studied scheme: 1 FPU about 3 hours, 2 FPU about 4 hours, 3 FPU about 5 hours, and 4 or more FPU about 8 hours. Longer windows match the slower digestion of larger fat loads.
What is a dual-wave bolus?
A pump bolus split in two: an immediate portion for carbohydrates and an extended portion spread over hours for fat and protein. It mimics natural insulin release better than a single bolus for mixed meals.
Does the Warsaw Method work for type 2 diabetes?
It was designed and studied for type 1 diabetes on insulin pumps. People with type 2 on oral medications or basal insulin follow different strategies; the extended-bolus concept needs pump control to implement.
Why does pizza spike blood sugar so late?
High fat slows gastric emptying and protein converts to glucose gradually, pushing the rise 3-5 hours after eating. Carb-only insulin peaks early and fades, leaving the late rise uncovered, the exact gap FPUs address.
Is the carb equivalent exact?
No, 10 g per FPU is an empirical approximation from the Polish studies, and individuals vary. Diabetes teams individualize the conversion from glucose logs rather than trusting the raw number.
Can I use this on multiple daily injections?
Not directly. Injections cannot easily deliver an extended bolus over hours, which is why the method is pump-specific. MDI users should discuss split-dose strategies with their team instead.
What are the risks of getting it wrong?
Too much extended insulin causes delayed hypoglycemia hours after the meal, which can be severe. Too little leaves prolonged hyperglycemia. Both are why every change needs clinician supervision.
Who should I talk to before trying this?
Your endocrinologist or certified diabetes educator. Bring the FPU numbers and your glucose logs; they will set the actual ratios and bolus patterns for your pump.