Petition to Tandem

Yesterday’s post has really had me thinking. More people have also stated that this is a big deal to them as well. And, since with medical companies and organizations, change happens when more people speak out, I thought I’d make a way to have an organized “voice”. A petition.

In short, what we want them to change is the way the bolus calculates your meal bolus based on your blood sugar. The insulin-on-board is tracked for every bolus -whether it’s correction or meal. Well, here’s a scenario where their 70 mg/dl limit for “reverse correcting” is a problem….

Let’s just say it’s 10:00 am – Your bg is 220, so you program your pump to give you a correction bolus of 2.3 units to bring you down to your target of 120.

Now, it’s 12noon – time for lunch. You check and to your surprise, your bg is actually 88. Whoops. So, since you only bolused 2 hours ago, you still have insulin working too, around .98 units actually.

If you add in your carbohydrates, it calculates for those.. let’s say 36g of carb, and based on an insulin-to-carb ratio of 1 unit per 10 grams of carb, it will tell you that you need to bolus 3.6 units for your lunch.

But wait….

What about that 0.98 units that’s still working? Since you’re purely bolusing for your meal, wouldn’t that 0.98 still be working also? And since you’re below your target, shouldn’t that be subtracted out?

The t:slim doesn’t subtract out that IOB unless you’re below their pre-set 70mg/dl. If my blood sugar had dropped to 69mg/dl, it would subtract it from the 3.6.

In theory, wouldn’t you want your bolus to bring you to your target bg and not lower? Based on the way this is calculated, your blood sugar would actually fall past your target and back down to 88, and probably lower. How?

Your meal bolus (should) bring you back to your pre-meal range, within 30 mg/dl of it at least. Let’s just say in a perfect world, that I did return to 88. That 0.98 units would have been added to the 3.6 in my insulin-on-board, making it 4.58 units. Let’s just say that my correction factor is 1 unit for every 44 mg/dl. Given this math, by the time all of the insulin had finished working, my blood sugar would level out at around, oh, 35-45 mg/dl.

Now do you see why this is so important to me? Important to a lot of us?

Please, if you can, take a minute to sign this petition. Even if you aren’t a t:slim user. We need this change.



Filed under dblog, Diabetes

10 responses to “Petition to Tandem

  1. This seems very unsafe to me.

  2. c.a. costova

    I have this situation a lot so instead of the full bolus for a meal or snack I cut down the amount of the Carbs I put in by quarter or half. It usually works.

  3. I am not yet a T-slim user( soon), but I wish it had a manual bolus feature, for this reason. I almost always do manual boluses.

    • sarahkaye

      There is a way to do manual boluses by using the quick-bolus function. It’s not as easy as just typing it in, but it does work. Another way to do it is by entering in 1 gram of carb then manually over-riding the suggested bolus. 🙂

      • Susan

        Also, once you calculate your bolus you can tap the result and “override” or type in your desired amount.

  4. adrianne

    I know that you said you had insulin on board does it take into consideration how long your insulin is active? I’ve had to change mine with the minimed for the same reason. Mine is down to 2 hrs, which isn’t common, but it works better for me.

  5. Tina H

    I’ve never had an issue at all this month with this. Dunno

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