Wednesday, February 2, 2011

Insulin sensitivity

Oh insulin sensitivity you confound me. Seriously. Grace's have been puzzling me lately. Basal rates are good, they hold steady when she doesn't eat and they held her steady when she caught the stomach bug. Her I:C ratios work, they bring her within range after eating a specific carb count meal. It is her insulin sensitivity ratio that puzzles me, it just doesn't compute.

So, insulin sensitivity, otherwise known as the correction factor. In plain and simple terms, it's how much one unit of insulin brings blood sugar down. So it's a ratio. 1:100, 1:60, 1:300 - whatever works for your child and brings their high blood sugar down. It's also based on a calculation from one's TDD (Total Daily Dose) of insulin. So it has a basis, proven by the reduction of a blood sugar from a high. When she was first diagnosed, Grace's correction factor was 1:180, then 1:150 for a very long time. It's still in my head, 1:150, it was that number for so very long.

For the last year almost, they have been 1:80 during the day from 8am - 8 pm, then 1:90 from 8 pm to 8 am. One unit affected her less at night than during the day. She needed less insulin at night to bring her down than during the day. Within the last 3-4 months, things have changed and I have worked my tail off to figure them out correctly.

Grace would sometimes run a high at her bedtime check at 8pm, often from a carb guess from homemade dinner. There would be no insulin in board from eating, and none from a correction. I would bolus to correct the high, but 2 hours later, find that I had overcorrected, thus bringing about a low that needed to be corrected the other way. So she would be at a perfect night-time BGL, but there would be IOB that I know would cause her to crash. There is nothing I dislike more than ping-ponging between highs and lows. So I do my best to avoid it at all costs. And I must say, it's something Grace rarely does lately - EXCEPT for this darn correction factor! The correction factor of 1:90 was giving her too much insulin. I could feel it. So I raised it to 1:100 at night.

Only that was also giving her too much! So I then changed to 1:110 just three weeks ago.
Still too much. Still leaving IOB that causes crashes.

Then two week go, I changed it again to 1:130.
Another high at night after dinner, a correction and dang it all, another come within range within one hour, then a .30 IOB with a BGL of 130, which will result in a low at night, when she's sleeping.

So, I've done two things, lowered her I:C ratio at dinner so she gets more bolus for her dinner, thus not giving us this problem in the first place. And I've upp'ed her correction factor again!

She is currently at 1:160 at night......... Ok, four weeks ago she was 1:90.
Growth hormones? Increased activity levels?

We haven't had a high at night since last Thursday to correct, so I wait.

So you would think I have it figured out now huh?! I don't!
You wanna know why???
It's John Walsh's fault!
THIS sits in the back of mind. THIS haunts me day and night, taunting me, saying, something is wrong, other than her correction factor.
Her TDD averages 28 - 30 units per day. We use a 60/40 split on bolus/basal.
Her correction factor should be nearer 1:69 or 1:60!!!!!

So I did a little test... I programmed that correction factor ratio into her PDM of her OmniPod.
What would a correction factor of 1:60 give her in units of insulin as compared to 1:160?

Grace's range is 80-150 with a target of 120.

And here's what it said to me:
High of 250 BGL at correction factor of 1:160 = .80 units  
High of 250 BGL at correction factor of 1:60 = 2.25 units

What a difference in dosing!

So, for now, we are 1:100 during the day and 1:160 at night.

Why is Grace defying some standard conventions of diabetes management?
Oh yeah, that's right, she has Type 1.


Hallie Addington said...

I SO feel your pain on this. We struggle with ISF all the time. Sweets isn't even on that chart... And any correction AT ALL overnight starts her dropping and she doesn't stop. Her current ISF at night 1:500. Yes. 500. And she still often goes low. WTHeck? Until this week....when it's not enough. *sigh* If only it was a = b = c! Good luck, my friend!

Donna said...

Our endo has this thing... it secretly drives me nuts but I often find myself thinking it.

Whenever I am in his office and complaining that the numbers aren't computing or just dont make sense... he will look at me over his little glasses and say, "Well, ya know - Diabetes likes to play with you like that."

And thats it - that's all he has to say. LOL

But it's SO TRUE!!!!!

Meri said...

Oh that is right...she isn't a sheet of paper! She is a human being! Keep up the good work!

Joanne said...

I'm betting Elise wouldn't even be on that chart! Her correction differs depending on which way the wind is blowing. Right now we can only use diluted to correct Elise, and 1 unit brings her down about 100, which if it were full strength would be 1:500.

We can't even correct at night unless she's at 400 or else she'll bottom out.


Unknown said...

I heart your wicked pancreatic, insulin dose, correction calculating, carb ratio tweaking, chart studing self!!! Penny you are a ROCK STAR at this stuff. And, yeah, unfortunately this people's, our children's, blood sugars decide to fluctuate against all scientific data and research. THE NERVE!

Great post. VERY interesting, as always.

Holly said...

Hey there! found you on Hallie's page!! : ) just my tiny two cents...we have more than 2 ratios per day. My daughter's mornings (6-9am is the highest ratio, followed by 9-midnight). She's 8, so maybe her ratios are similar? Her correction ratios are:
12am-6am 1:165
6am-9am 1:110
9am-9pm 1:230
9pm-12am 1:118
We are far from perfect (haha!!), but I don't get too scared to correct at night anymore. I have noticed if she even loses two pounds from a virus or swimming in the summer, I have to drop her basal by at least 10%! Can you drop her basal by % on your pump? It lets you control smaller numbers than dropping by .05/hour. : ). I've never had anything but Medtronic, so I'm unfamiliar with other pumps. : (

Anonymous said...

We aren't even there yet...I'm confused just reading this post. One month into Parker's diagnosis, they keep us on a tight leash and only give us tiny bits of information at a time....I'm sure because it would blow our minds. He is honeymooning so bad right now that he doesn't get the long acting insulin or meal dose at all anymore in the morning. Poor guy thinks he has permanently switched to two shots a day instead of four and doesn't realize this honeymoon phase is temporary. Did your daughter go through a long honeymoon phase?

Alexis Nicole said...

J and G are going through the same thing. Js is 1:80 but at night any correction crashes him. Ive started with basals and dinner ic for now...

Anyway youre simply fantastic how you figure it all out!

Lorraine of "This is Caleb..." said...

Caleb actually needs about twice the insulin at night for a correction. Twice. And I can't allow myself to be haunted by what he's "supposed' to be. It's nice to have a gauge as a starting point, but the books don't always have the answers (unfortunately).

Anonymous said...

John Walsh's charts are great but the correction factors are WAY off for a lot of children. Maybe even some adults. Calculation I have found that works for me is to use Walsh's correction factor but not use the TDD but the total daily basal. Which can be anywhere from 40 to 60 percent of TDD. So if she has a TDD of 50 and a total daily basal of 25, I use Walsh's calculations but plug in 25 (total basal) as the fake TDD. However, for years, her correction factor was higher. I would rely on endo to trouble-shoot the ISF. Then increase or decrease by ten. And I still go up and down by ten and have endo look it over. When trending high, she needs lower correx factor; when trending low, she needs higher. But it is fairly stable within that range.