I have read differing data on the topic of caloric absorption values from the PD solution. One source suggested that as much as 1/3 of my daily calories (~700-800) could be coming from the solution, others seem to suggest less As a Type-I diabetic this is of course a concern and I have been gaining weight even since I went to PD (roughly a pound a month). I generally keep to a very low carb diet and was taking 40~45 units of insulin per day, but now with PD this has increased to 55 or more, mostly at night when the exchange takes place (and A1c is rising as well) - that 20% more insulin! I use a 50/50 mix of 1.5% and 2,.5% PD solution and seem to get good clearance rates with this (and 7.5 during the day dwell), but I am now wondering if I should try a straight 1.5% solution for a while to see if the sugar intake will be reduced.
I have two questions from this. One, what is the current thinking regarding how much sugar one absorbs from the solution? What is the equivalent sugar density that each has (at what blood sugar would it equalize)?
Two, how does one choose between a lower percentage fluid and a shorter dwell time to optimize the results (thankfully I am a high transport)? And, is there any benefit to using the higher percentage fluid first or second to better match my own overnight sugar levels. (I understand how they mix ratios as each fill progresses, can one use this effect to have a stronger mix when my own sugar is higher)?
Hi DC,
Wow, great questions–and largely beyond my level of expertise as a non-MD or nurse. Beth has some PD nurses that she will check in with, and we’ll get back to you with what they say.
In the meantime, the info I’ve read (Carol Ireton-Jones. Handbook of Home Nutrition Support. Jones and Bartlett, 2007. Boston, Toronto, London, Singapore) suggests that 75% of the calories from dextrose in PD fluid are absorbed:
– 1.5% fluid - 15 grams of dextrose (75% absorbed = 11.25 grams) - 3.4 calories/gram = 38.25
– 2.5% fluid - 25 grams of dextrose (75% absorbed = 18.75 grams) - 3.4 calories/gram = 63.75
– 4.25% fluid - 42.5 grams/dextrose (75% absorbed = 31.875 g) - 3.4 calories/gram = 144.5
I can’t guarantee that this is the “final thinking” on absorption, but it’s a pretty recent source. If you are mixing bags, you’d need to do some calculations to figure out the grams of dextrose you’d end up with.
In general, you want to use the lowest bag possible to pull off the water. The dextrose is used to create a concentration gradient that will pull water out of your blood and into the dialysate–but some of the sugar caramelizes during the manufacturing process, creating by-products called glucose degradation products, or GDEs. Exposing the peritoneal membrane to GDE’s can cause damage over time that eventually can reduce its ability to be a useful filter for dialysis. The higher the % dextrose in dialysate, the more GDEs it contains. (NOTE: Some people are warned off of microwaving dialysate because of fears of GDEs–but they are not created in the microwave, only in manufacturing. If you DO microwave PD fluid, it’s important to mix it well to avoid “hot spots” and burns, but it won’t harm your membrane any more than fluid heated by other means).
I’m not quite clear on why you would want to “match” your overnight sugar levels. Wouldn’t you just want to minimize them? At any rate, we’ll ask a PD nurse and see what we can learn for you. 
> 25 grams of dextrose
Wow, thats a lot. One question: it that “per bag” or “per kilo/liter”? That’s about the same as drinking a coke (something a brittle diabetic would never do). Any idea what the equivalent blood sugar would be?
As I am on the cycler, I don’t have to heat the bags. Its interesting that microwaves don’t cause caramelization, I thought any heat source did this (starch + heat = sugar)
“Matching”: is necessary because I, like one out of 5 uses, don’t really get a 24 hour duration from “Lantus” inulin, its more like 10 hours, so we take it twice a day. The dose at bedtime is now much larger due to the PD fluid sugar and I have to purposefully “drive up” my blood sugar to about 150 before to avoid a low during the night. Thus, I choose to use the 2.5% fluid first (so I get the larger gradient at first). Its a rather minor point, but in one case you get filled with these percentages: 2.5, 2.25, 2, 1.75, 1.5, if you reverse how you connect the bags, the percentages are reversed as well.
Hi DC,
My understanding is that the calorie numbers are per bag.
Ohhh, now I get the “matching” you’re doing. Are you by any chance using an insulin pump? You sound extremely knowledgeable, and pumpers tend to be at the upper end of the self-management continuum of folks with diabetes.
[QUOTE=Dori Schatell;18532]
My understanding is that the calorie numbers are per bag. .[/QUOTE]
Then what size bag was used. As you know bag sizes vary by a factor of six (from one to six litters).
I guess we can presume 2L until we learn. Based on that and what you stated before, looks like ~ 107 absorbed calories per session in my case. That would be about 5% of my intake, does not seem right. If the these values were “per liter” then with 10 L of solution we would have ~510 calories, which is about a 1/4 of a 2000 a daily diet If these values were “per bag” (and a bag is 2L) then with 10 Ls of solution we would about 2/5 of this or 204. Too many numbers, my head is spinning 
But experience has taught me that 40 grams of dextrose is sufficient to drive me into the high 300’s blood-sugar wise.
Are you by any chance using an insulin pump?
I have a needle phobia that is rather extreme so that one won’t do for me. I use a needle-less system (a product called Medi-Jector) that uses pressure and laminar flow technique to form the needle out of the stream of insulin itself. Perhaps after the transplant (~6moths) I may give a pump a try as so many people tell wonderful stories of better control with a pump,. but I will need to unlearn a few habits first.
Oops, I was wrong: the dextrose figures are per liter. Absorption of sugar from PD dialysate also varies depending on:
– Your metabolism in general
– Your peritoneal membrane and how well it transports
– Dwell time (you might absorb 60% of the dextrose calories in a short dwell, but as much as 80% in a longer one).
So, the only way to really tell what the impact of a particular bag is on you would be to test your sugars.
At least this isn’t complicated. 
So that means about ~510 adsorbed calories in sugar each night, reason enough to talk to the Doc about using a straight 1.5% mix to reduce to ~380 per night. This also tracks with the additional ~15 units of insulin a day that I have had to take since PD started.
I drain an avenge of 500mL each night (although you need to low pass filter this and plot it to see it, the daily variation is quite large), and that seems adequate (even to the point of leg cramps). I don’t know of any way to predicate what drain I would get with a lower percentage solution other than to try it for a week or so.
I am not sure the average dwell time, there are four fills in nine hours but it seems to me (just from watching the machine) that dwells; vary over the night from 1.5 hours to a shorter time latter in the night. I use Icodextrin during the day dwell, so I am not too concerned about losing the removal of “middle molecules” if the night dwells are shortened a bit.
Dori, Thanks so much for the data here, I think this will be a rich topic to discuss with the doctor (once we overcome a related issue about patent extensions).
After a visit with the doc today, I will try overnight dwells with a straight 1.5% and see what the reduced sugar absorption will be and what nightly drain levels I get. The doc concurred there was some room to play and tune this better.
