Dual Wave Bolus

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Permalink Reply by Ricardo on October 29, 2009 at 10:08am

Hi Danny,

From the example you gave, it appears TAG could help you.

I am assuming you counted the carbs in the chicken wings and sauce and calculated the bolus based on the carbs only , using a dual wave bolus. If this is the case, you used the grams of carbs with your i:c ratio to come up with how much insulin you needed to cover the meal

If you added up all the insulin you needed to cover this meal over the 8 hour span (initial up front bolus + square wave + corrections), you will see that it is a quantity of insulin that exceeds what you would have calculated based on the carb count and your i:c. TAG explains it by saying that you only counted the direct carbs without accounting for carbs produced by the proteins and fats in your food.

The standard TAG formula says that approximately 50% of the protein in a meal will be converted to glucose and about 25% of the fat will be converted. I tweaked those numbers for my metabolism. Carbs coming from the conversion of proteins and fats to glucose is a slow process and will affect you hours after the meal.

Using your example of 1.5 units up front and 3 units over 3 hours meant that your square wave was set at a rate of delivery of 1 unit per hour (3 units/ 3 hours). This rate of delivery was great for you because it kept your BG stable. You were delivering the insulin at a rate that matched your body's metabolism of the protein and fat in the meal. If you simply stretched those 3 units over a longer time, the rate of delivery would have been less and most likely you would have seen you BG increase.

It looks like you needed that 1 unit per hour delivered for a longer period of time than 3 hours. TAG would have told you you had some additional carbs to account for and would have had you extend the square wave for a longer period.

One way to figure it out would be to take the correction you took and add it to the square wave, while keeping the rate of delivery at 1 unit per hour.

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Permalink Reply by Danny on October 29, 2009 at 10:25am

Wow, Ricardo, thank you...I am going to Buffula Wild Wings for lunch today, ordering exactly the above meal and will try extending according to TAG. It seems as though I was doing a slightly different version of TAG. I had the thought process that the fat and protein would sooner or later increase my sugars and I would bolus + square wave at the 3 to 4 hours mark.

This is by far the most exciting news in my diabetes world in a long time.

Consider me a TAG'r :)

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Permalink Reply by Ricardo on October 29, 2009 at 11:14am

Danny,

Don't forget to take into account that if the meal is considered high fat, it may slow the metabolism of the carbs. In this case I move a portion of the upfront bolus into the extended so that I don't drop low early on.

It's trial and error when you start TAG.

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Permalink Reply by Ricardo on October 29, 2009 at 10:18am

Danny,

The 8 hour bolus can be a problem if it is stacked on top of an upcoming meal or exercise.

This is where you have to take into account the carb loading of the new meal or any upcoming activity.
For activity, you may have to cut or shut off the extended bolus. For a new meal, you would have to calculate a new dual wave which combines the new carb loading with the remainder of the unused portion of the previous extended bolus.

It gets complicated, but it works well when used correctly. The fact that it is complicated might be why TAG never really caught on and the book is now out of print.

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Permalink Reply by Danny on October 29, 2009 at 10:34am

I have been doing Diabetic math my entire life. For the results I am achieving it is worth the little bit of extra time and effort.

Thank you again for sharing your knowledge.

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Permalink Reply by Ricardo on October 29, 2009 at 11:09am

Danny,

I am just bumping part of the post which mentioned the TAG book since some may have missed it and wonder where TAG came from.

TAG is definitely more complicated, but our bodies are complicated. Many of the posts I have seen in this thread are just dual waving the carbs, whereas TAG accounts for the effect that proteins and fats will have on your BG.

I read about TAG in Total Available Glucose - A Diabetic Food System, by Mary Joan
Oexmann MS RD, ISBN 0-688-10004-X

It appears the book is out of print. It was published in 1989 and 1990.

The book only had about 2 pages that talked about TAG, so it is not even worth getting. If you understand the principle, you can make TAG work for you.

If you insist on reading it for yourself, used copies are available at Amazon.com for a penny plus shipping.

http://www.amazon.com/gp/offer-listing/068810004X/ref=dp_olp_0?ie=U...

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Permalink Reply by Grace on October 29, 2009 at 6:10pm

Ricardo & Danny,

You guys rock.

I'm loving this discussion; but I can't help playing devil's advocate for a second. WHAT IF... all of our i:c ratios are wrong because we do bolus testing on meals with some fat and protein. SO... the TAG method is working because it effectively increases our total insulin for the meal, and also stretches it out over time to mimic both second phase insulin release and slower digestion of carbs when they are "encased" in fats and proteins. The method works, not because 25, 40 or 50% of fats and proteins are actually converted to carbs, but because it mimics normal digestion much better and solves the accuracy problems inherent with bolus testing. Is this just another way of looking at it, or does this explanation miss some aspect of why these square boluses work so well?

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Permalink Reply by Ricardo on October 29, 2009 at 8:44pm

Hi Grace,

You can test this theory very easily.

If the success of TAG is due to faulty i:c ratios, the TAG i:c ratio should still work if you ate a carb only meal. I know in my case it would be way too much insulin, even if I spread it out with a dual wave.

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Permalink Reply by Maria on October 30, 2009 at 7:07am

This is SO helpful. I have had great numbers for the past few days. I wonder if those of us doing lower-carb diets find the TAG more helpful - because maybe more of our protein and fats are being turned into glucose. I know I've been kind of frustrated by the 1500 and 1800 rule that don't seem to apply to me at all and by the constant statements of "you only need to bolus for carbs" and "fats do not raise blood sugar." So hearing that some of you, like me, have to bolus for protein and fat makes me believe that I"m more normal than I thought.
Maria

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Permalink Reply by Ricardo on October 30, 2009 at 11:44am

Hi Maria,

TAG makes a lot of sense, when you consider that the body cannot store excess protein when you eat, so it converts any excess protein, above and beyond what you need to repair your body, to glucose as an alternative energy source. It does the same with fat to a lesser extent.

Our brain needs carbs to function. Gluconeogenesis is a back up source of carbs, especially if we restrict them in our diets. For many of us, if we do not account for this in bolusing, we will tend to have a lot of unexplained highs.

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Permalink Reply by Kelly Rawlings on October 30, 2009 at 12:10pm

I remember when carb counting came into vogue and my CDE mentioned I needed to dose only for the carbs! Hah!

With absolutely no self-insulin production as a type 1, I just don't think this is solid science.

I've greatly simplified my TAG math by automatically including 1 unit of fast-acting for a "normal" protein meal (about 4-6 grams of protein from any source). This is my cheater way of doing it :-) since I'm too lazy to do all that assessment of my metabolism (unlike Ricardo, who rocks).


Another thing that makes life (and our math) so complicated is that few of us eat a meal composed of only one type of nutrient. So those cashews that seem like mostly fat? They actually have 7 grams carb, too. And that much carb, although slower to act, is nearly equal to 2 glucose tabs.

Different is the new normal, right?!

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Permalink Reply by Ricardo on October 30, 2009 at 6:06pm

Hi Kelly,

I am happy that you find some value in the TAG info.

I agree that carb only bolusing is not solid science, at least for some of us. Like you, I am a Type 1 with no first or second phase insulin release, so TAG is simulating that dual phase release for me.

Carb only bolusing fails to account for the interaction of nutrients in a food. The best example of this is pizza. If you just ate the crust of a pizza, for most of us, our BG would spike in a short period of time. Add a little tomato sauce and cheese to the crust and all of a sudden the carbs are absorbed slower and you may need extra insulin to cover the protein and fat. TAG is better at accounting for nutrient interactions than carb only bolusing.

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