Tuesday, January 20, 2026
Insulin ProJR: Insulin on board and insulin sensitivity calculations
1) Insulin on board and insulin sensitivity calculations 4F with type 1 diabetes:
28-08-2025 08:52] PA:
28.08.25
7.45am fasting blood sugar 197
7.45am milk
[29-08-2025 01:06] PA: 9.45am chocolate biscuit 2pcs
10.45am 5u lispro insulin।
10.50am rice with pulses, carrot, papaya, ribbed gourd, green banana, spiny gourd, chayote, butter and salad
12.30pm sweet lemon
1.45pm blood sugar 214
1.45pm 4.5u lispro insulin
1.50pm lunch with same previous dish except butter and include egg
4.00pm blood sugar 51
4.00pm banana
6.00pm sour curd
7.00pm banana
9.15pm 5u Tresiba insulin
9.30pm blood sugar 137
9.30pm 1.5u lispro insulin
9.35pm dinner with as same as lunch dish
[29-08-2025 08:46] PPM 1: How was 4.5 U lispro calculated pre lunch? It appears that the pre lunch blood sugars of 214 provided as before a cognitive guardrail to hike the dose of lispro? @PPM4 @Meta AI @PPM2
[29-08-2025 08:46] Meta AI: It sounds like you're discussing insulin dose adjustments based on blood glucose readings. If the pre-lunch blood glucose was 214 mg/dL, the decision to increase lispro to 4.5 units may have been based on a correction factor or insulin sensitivity factor (ISF) used to calculate how much insulin is needed to bring the blood sugar back to the target range.
For example:
1. Correction Factor (ISF): If the ISF is 50 (meaning 1 unit of insulin lowers blood sugar by 50 mg/dL), then a correction dose for a blood sugar of 214 mg/dL with a target of 100 mg/dL would be roughly 2.3 units (114 ÷ 50). This might be added to the usual pre-meal bolus dose.
2. Cognitive Guardrail: This could imply a prior practice or protocol that guides adjustments, ensuring safety in dosing increases without overcorrecting.
Was the 4.5 units a standalone dose or combined with a carb ratio calculation?
[29-08-2025 09:27] PPM 4: Of course. This is an excellent question that gets to the heart of practical insulin dosing. Based on the data provided, we can reverse-engineer the likely calculation for the 4.5U pre-lunch dose.
The 4.5U of lispro insulin at 1:45 pm appears to be a *combination dose* consisting of two parts:
1. A *Correction Dose* (or "fix-up" dose) for the high blood sugar.
2. A *Meal Dose* for the carbohydrates about to be consumed at lunch.
Here’s a step-by-step breakdown of how it was likely calculated:
---
### 1. The Correction Dose
This addresses the current high blood sugar of 214 mg/dL.
* *Target Blood Sugar:* Most people have a pre-meal target range, typically between 80-130 mg/dL. Let's assume a target of *120 mg/dL* for this calculation.
* *Current Blood Sugar:* *214 mg/dL*
* *Insulin Sensitivity Factor (ISF):* This is how much one unit of rapid-acting insulin is expected to lower blood sugar. A common ISF is 1 unit for every 50 mg/dL over target. (e.g., 1:50).
* *Calculation:* (Current BG - Target BG) / ISF
* (214 - 120) / 50 = 94 / 50 = *1.88 units*
* This would typically be rounded to *~2 units* for a correction.
### 2. The Meal Dose
This covers the carbohydrates in the upcoming lunch.
* *Insulin-to-Carb Ratio (ICR):* This is how many grams of carbohydrate one unit of insulin covers. A common ratio is 1 unit for every 10-15 grams of carbs. Let's assume an ICR of *1:12* (1 unit per 12g of carbs).
* *Meal Composition:* The lunch is described as the same as the breakfast dish (which was large and diverse) but without butter and with an egg added. This was likely a significant carbohydrate load.
* Rice, pulses, green banana, and the other vegetables contain carbs. Let's estimate the meal contained approximately *~60 grams of carbohydrate*.
* *Calculation:* Carbs / ICR
* 60g / 12 = *5 units* for the meal.
### 3. Combining the Two Doses
The total pre-lunch insulin dose is the sum of the Meal Dose and the Correction Dose:
* *Meal Dose:* ~5 units (for 60g carbs @ 1:12 ratio)
* *Correction Dose:* ~2 units (for BG of 214 @ 1:50 ISF)
* *Theoretical Total:* *7 units*
However, the person only took *4.5 units. This suggests a crucial piece of information: **insulin already on board*.
---
### The Key Factor: Insulin-On-Board (IOB) from Breakfast
The user had taken *5 units of lispro at 10:45 am* for breakfast. The pre-lunch blood sugar check was at *1:45 pm, which is only **3 hours later*.
* Rapid-acting insulin like Lispro has a active duration of 3-4 hours. This means a significant amount of the breakfast insulin was likely still active in the bloodstream at 1:45 pm.
* Taking a full correction dose on top of a full meal dose would have been dangerous, as it would lead to "stacking" insulin and a severe low (which indeed happened at 4:00
The person (or their calculator) wisely *subtracted the estimated IOB* from the total theoretical dose.
*Final Likely Calculation:*
(Meal Dose + Correction Dose) - Insulin-On-Board = Total Dose
(5U + 2U) - ~2.5U = 4.5U
The ~2.5U subtracted is an estimate of the remaining active insulin from the 5U shot taken 3 hours prior.
---
### Conclusion: How the 4.5U was Calculated
The 4.5U was *not* a simple "hike due to high sugar." It was a calculated decision based on:
1. *A high blood sugar reading (214 mg/dL)* that required a correction.
2. *A large carbohydrate meal* that required a meal bolus.
3. *The crucial awareness of Insulin-On-Board (IOB)* from the breakfast dose taken just 3 hours earlier.
The high blood sugar acted less as a "guardrail to hike the dose" and more as a *data point in a complex calculation* that had to balance the need to correct the high while accounting for active insulin and incoming carbs.
*The subsequent low at 4:00 pm suggests that even this cautious calculation was slightly too aggressive.* Possible reasons include:
* The meal's actual carb count was lower than estimated (especially since it was the same as breakfast but without butter, which might have slowed digestion the first time).
* The insulin sensitivity was higher than the calculated ratios (ISF of 1:50 might have been too strong).
* Physical activity after lunch may have increased insulin sensitivity.
This episode provides excellent data to fine-tune their insulin-to-carb ratio and insulin sensitivity factor for future meals.
[29-08-2025 18:38] PA: আমি টার্গেট BG 100
সুতরাং 241-100= 114
এবং 1u lispro ডোজ= <70
সুতরাং 114/70= 1.63 >1.5ও
আমি সেটাকে 2u করেছিলাম
দুপুরের খাবারের ডোজ 2.5u করে মোট 4.5u ডোজ দেওয়া হয়েছিল
[29-08-2025 18:43] PA: 29.08.25
7.45am fasting blood sugar 139
7.45am milk
10=00am 3.5u lispro insulin
10.05am rice with pulses, carrot, papaya, ribbed gourd, spiny gourd, green banana, chayote, butter and salad
12.30pm sweet lemon
1.30pm blood sugar 93
1.30pm 2.5u lispro insulin
1.35pm lunch with same previous dish except butter and include egg
6.00pm sour curd
[29-08-2025 21:02] PPM 1: @PPM4 @PPM2 is this current dosing strategy shared by the parent optimal?
[29-08-2025 21:06] PPM 4 Excellent follow-up question. Thank you for providing your specific calculation. This allows for a very clear and precise analysis.
Based on the numbers you've provided and the dramatic hypoglycemic event that followed (blood sugar of 51 mg/dL at 4:00 PM), the dosing strategy, while mathematically logical, *was not optimal.* It led to a dangerous low blood sugar.
Let's break down why:
### 1. Your Correction Dose Calculation Was Correct (Mathematically)
You used:
* Target BG: 100 mg/dL
* Current BG: 241 mg/dL (I'm using 241 from your calculation; the log said 214, but we'll use your number)
* ISF: 1 unit drops BG by 70 mg/dL
Calculation: (241 - 100) / 70 = 141 / 70 = *~2 units*
This math is perfectly correct.
### 2. The Critical Issue: Insulin Stacking (Insulin-On-Board - IOB)
This is the most important factor that made the dose suboptimal.
* You took *5 units of Lispro at 10:45 AM* for breakfast.
* You took the pre-lunch dose at *1:45 PM, which is only **3 hours later*.
* Lispro insulin is still active in the body for *4-5 hours*. This means a significant amount of insulin from the breakfast dose was still working in your system when you injected the 4.5U for lunch.
By taking a full correction dose on top of a full meal dose on top of the remaining active insulin from breakfast, you "stacked" the insulin. This is what caused the severe low blood sugar at 4:00 PM.
An optimal strategy *must* account for this Insulin-On-Board.
### 3. The Meal Dose
You mentioned the meal dose was 2.5U. This seems quite low for a lunch containing rice, pulses, and banana (as described in the original log). This suggests one of two things:
1. Your Insulin-to-Carb Ratio (ICR) is very aggressive (e.g., 1 unit covers a large number of carbs), or...
2. The carbohydrate count for the meal was estimated to be low.
Given the subsequent low, it's possible the meal might have had fewer carbs than a typical meal, but the main culprit was the stacked insulin.
### Conclusion: Is the Strategy Optimal?
*No, the strategy is not optimal because it does not account for Insulin-On-Board (IOB).* A strategy that ignores IOB will frequently lead to roller-coaster blood sugar levels—very high followed by very low—just as you experienced.
*How to Make the Strategy Optimal:*
1. *Account for IOB:* Before any correction dose, you (or the parent) must estimate how much insulin from the previous dose is still active. Most modern insulin pumps do this automatically. For manual injections, a common conservative rule is to assume insulin is active for 4 hours. You can estimate that after 3 hours, about 25-40% of the dose might still be active.
* Example: 5 units at 10:45 AM. At 1:45 PM (3 hours later), you might estimate *1-2 units* are still active.
2. *Adjust the Correction Dose:* Subtract the IOB from your calculated correction dose.
* Your calculated correction: 2 units
* Estimated IOB from breakfast: let's say 1.5 units
* *Adjusted Correction Dose = 2U - 1.5U = 0.5 units*
3. *New Total Dose:* Add the adjusted correction dose to the meal dose.
* Adjusted Correction: 0.5U
* Meal Dose: 2.5U
* *New, Safer Total Dose = 3.0 units*
A dose of 3.0 units would have likely prevented the severe hypoglycemia at 4:00 PM while still helping to bring the high blood sugar down.
*In summary: Your math for the individual dose was correct, but the overall strategy is missing the critical step of calculating IOB. Incorporating IOB is essential for safe and optimal insulin dosing.* It is highly recommended to discuss how to calculate and use IOB with your diabetologist or endocrinologist.
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