value of Stomach Glu After Dosing_insulindemo

Hi,

I would like to know if someone knows why the value of parameter Stomach Glu After Dosing in the insulindemo from the Toolbox SimBiology® takes the value of 125 gr knowing that the value of the dose is 78 gr ?

Thank you very much for your help,

Juliana

Answer 1

[Arthur Goldsipe]

I believe you are referring to the value of 125 in the variant named "Type 2 diabetic", as shown for example on this page. I believe I created this variant with the intention of simulating a meal containing 125 gram of glucose. In practice the initial value of this parameter (which is what the variant sets) will have very little impact on the simulation results. The value of the parameter is updated by an event whenever a dose is applied to the model. To eliminate confusion, I will remove this parameter from the variant.

Update: As described in the comments below, the initial value of this parameter does affect the simulation results due to a modeling error. Specifically, the event that updates Stomach Glu After Dosing imcorrectly updates parameters a and c. See my comment below for more details and a suggested fix.

[Carmen Juliana Gonzalez]

Hi Arthur,

Thank you very much for your answer.

I believe you are referring to the value of 125 in the variant named "Type 2 diabetic", as shown for example on this page.

>>Yes I am refering about this value.

However when you say that the initial value have little impact, well I am not sure about it. There are two parameters a and c that will change their value depending on the size of the meal. If you use the size of the meal 125gr, the values of a=6.25ea0-5 and c = 0.00023. But if you use a meal size of 78 gr, the values of

a= 0.0001 and c=0.0003. and looking at the .csv file of the simulation the value for the meal size that arrives to the variable Stomach Glu Solid is 78 gr.

The value of the parameter is updated by an event whenever a dose is applied to the model. To eliminate confusion, I will remove this parameter from the variant.

>> It is not the case for the first 3 lines of the .cvs file. I attached images of the .csv file after simulation and using a meal size of 100 gr.

This image shows that the meal size is 100gr.

Then looking to the next columns,

you can see that the first 3 lines of Varname16 = Stomach Glu After Dosing the values used is 125 and the it changes to 100. But if you look the next two columns e05 = parameter a and VarName18 = parameter c

the calculated values corresponds to a meal size of 125 for the whole columns.

I hope you can help me to clarify this.

Have a beautiful day,

Juliana

[Arthur Goldsipe]

Ah, you're absolutely right. This is yet another modeling error on my part. My intent was that the event that updates Stomach Glu After Dosing also updates parameters a and c based on the new value of Stomach Glu After Dosing. However, I forgot or misunderstood details of how events work. As described here, a and c do get updated but they use the old value of Stomach Glu After Dosing. Note that this issue likely affects all simulations. That is, regardless of whether this variant used, the values of a and c are not updated properly after a dose. The easiest short-term fix would be to update the event functions for a and c, replacing [Stomach Glu After Dosing] with Dose+[Glucose appearance].[Stomach Glu] (which is the new value for Stomach Glu After Dosing). In the longer term, I want to review this model to see if I can clean it up. I can take advantage of new features and my better understanding of the product to implement the model in a better way.