How this instrument works
Carbohydrate raises blood glucose quickly, and standard bolus calculators dose for it directly. Fat and protein also raise blood glucose — just more slowly, over a longer window — which is a problem for a single up-front bolus timed to carbohydrate alone: it can undertreat the delayed glucose rise from a high-fat, high-protein meal. The Warsaw method, described by Pańkowska and colleagues at the Medical University of Warsaw, converts the calories from fat and protein into a carbohydrate-equivalent dose that a pump's extended or dual-wave bolus feature can deliver over time (Pańkowska E, et al., Pediatr Diabetes, 2009).
The conversion runs on fat-protein units (FPU): fat contributes 9 kcal per gram and protein 4 kcal per gram, and 100 kcal from fat and protein together equals 1 FPU. Each FPU is then treated like 10 g of carbohydrate — so the fat/protein calories are converted to a carbohydrate-equivalent in grams, and that carb-equivalent is dosed using the same insulin-to-carb ratio already used for ordinary carbohydrate.
This calculator deliberately stops at the dose. It does not compute how many hours to spread the extended bolus over — that duration depends on the specific pump, the meal, and individualized guidance from a diabetes care team, and the duration-by-FPU figures found outside the primary literature weren't consistent enough to include here with confidence. Treat the dose as the FPU-based starting point the Warsaw method describes, and set the extended-bolus duration the way your pump and care team already direct you to.
This is a tool for people already using an insulin pump with dual-wave or extended-bolus capability, in coordination with a diabetes care team — not general dosing advice, and not a substitute for that team's guidance on ratios, targets, or bolus timing.
- Enter the meal's fat content, in grams.
- Enter the meal's protein content, in grams.
- Enter your own insulin-to-carb ratio (grams of carbohydrate covered by 1 unit of insulin).
- Read the fat-protein units (FPU), the carbohydrate-equivalent in grams, and the estimated extended-bolus dose in units. Bolus duration isn't calculated — that's set on the pump per your care team's guidance.
Worked example — three meals, three insulin-to-carb ratios
A meal with 20 g fat and 30 g protein — 180 + 120 = 300 kcal from fat and protein — is 3.00 FPU and a 30 g carbohydrate-equivalent. At an insulin-to-carb ratio of 1 unit per 10 g, that's an extended-bolus dose of 3.00 units.
A smaller meal, 10 g fat and 15 g protein (150 kcal), is 1.50 FPU and a 15 g carbohydrate-equivalent. At a tighter ratio of 1 unit per 8 g, the extended dose comes to 1.875 units.
A larger, richer meal — 40 g fat and 50 g protein (560 kcal) — is 5.60 FPU and a 56 g carbohydrate-equivalent. At 1 unit per 12 g, that's an extended dose of about 4.67 units. None of these three examples includes a duration: how long to spread each dose over is a pump- and care-team-specific decision this calculator doesn't make.
Questions
What are fat-protein units (FPU)?
FPU is the Warsaw method's unit for converting the calories in fat and protein into an insulin-dosable quantity. Fat provides 9 kcal per gram and protein 4 kcal per gram; 100 kcal from fat and protein together equals 1 FPU, and each FPU is treated as equivalent to 10 g of carbohydrate for dosing purposes.
Why do high-fat, high-protein meals need a different insulin strategy than carbs alone?
Fat and protein slow gastric emptying and get converted to glucose more gradually than carbohydrate, so they produce a delayed, prolonged rise in blood glucose rather than the faster spike carbohydrate causes. A single bolus dosed only for the meal's carb content and delivered up front can undertreat that later rise, which is why an extended or dual-wave bolus — spreading part of the dose over time — is used instead (Pańkowska et al., 2009).
Why doesn't this calculator tell me how long to extend the bolus?
Because a reliable, source-confirmed duration-by-FPU table wasn't available: figures found outside the primary literature weren't consistent enough to present with confidence, so duration was left out rather than guessed. How long to spread the dose over depends on your specific pump and your care team's guidance — check your pump's settings or ask your diabetes team.
Where does my insulin-to-carb ratio come from?
It's a personal ratio — grams of carbohydrate covered by 1 unit of insulin — that you and your diabetes care team have already established based on your own response to insulin. This calculator doesn't derive or adjust that ratio; enter the ratio you already use.
Is the Warsaw method identical on every insulin pump?
The underlying FPU math is the method itself, as described by Pańkowska et al. (2009). How a specific pump lets you program an extended or dual-wave bolus — and the maximum duration or split it supports — varies by pump model, so the mechanics of delivering the calculated dose should be checked against your own pump's manual.
Who is this calculator for?
People already using an insulin pump with dual-wave or extended-bolus capability, working with a diabetes care team on their carb ratios and targets. It isn't general public dosing advice, and it isn't intended for people who aren't already on pump therapy with this feature.
References
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.