19 Responses

  1. Elizabeth Joy
    Elizabeth Joy August 20, 2009 at 12:58 pm | | Reply

    Wow…These are SO far off from the settings I use. As a comparison:
    TDD=19.2 vs. 23 (my current setting)
    TBD=9.6 vs. 16(!!!)
    ICR=23 vs. between 18 and 21
    CF=78 vs. 128(!!!)

    I’m too scared to make any changes, though. This is just too radical of a change for me, especially since I’m really insulin sensitive and I’m doing well with my current settings (last A1C 5.6)

  2. Anne Findlay
    Anne Findlay August 20, 2009 at 4:28 pm | | Reply

    Interesting… I had an endo who kept thinking I should have higher basal rates but I resisted!

    My mean TBD/TDD over the past 10 days is 0.42.

    My mean TDD is actually 26 vs recommended 33, and mean TBD is actually 10.9 vs. recommended 13.2.

    However, these suggestions would also tell me to change my ICR from 17 to 9 which would drop me to the floor. The CR of 45 recommended by this method is accurate only if I am not exercising at all (like when I was immobile after getting injured). Currently I use 70.

    I wonder what other physiological parameters these factors could relate to, like metabolic rate etc.


  3. Henry
    Henry August 20, 2009 at 5:04 pm | | Reply

    It’s interesting to see that my current settings are almost completely aligned with the new recommendation.

    For a while I’ve been feeling that my settings are not right, as they don’t conform with the “standard”. Now I feel much better.


    Author of D and The Guy

  4. Lauren K
    Lauren K August 21, 2009 at 12:35 am | | Reply

    Wow. Reading this makes me never, ever want to try a pump. I don’t need another headache in my life. Injections are simple, straightforward, and portable.

  5. Lloyd
    Lloyd August 21, 2009 at 12:38 am | | Reply

    I’m an insulin dependent T2, producing very little insulin. C-peptide of 0.5. Here is how I adjust my pump:
    Adjust the basal so that the numbers are in line with my goals, and do not drift if I skip a meal. Insulin/carb and correction factors found by trial and error.
    30 day stats:
    Ave 94
    Standard Deviation 12
    26% bolus
    2% correction
    71% basal
    The above numbers are low on bolus, due to my eating a very moderate amount of carbs.
    I don’t see how anything derived from a formula can be anything but your first day’s settings, beyond that its all tweaking, basal first.

    Having your glucose remain as constant as possible when a meal is missed or delayed is a very useful thing. Combine that with good carb counting skills, and a food scale, and you can be very successful.


  6. Anon
    Anon August 21, 2009 at 6:43 am | | Reply

    These ratios work out to suggest that, on a perfect day without correction insulin, everyone — regardless of weight — eats 180 grams of carbs.

    We start with:
    TDD = 0.2 * weight
    Basal = TDD * 0.4

    Since TDD – basal = non-basal insulin (no corrections in an ideal world), we get

    non-basal insulin
    = TDD – basal
    = (0.2 * weight) – (TDD * 0.4)
    = (0.2 * weight) – (0.2 * weight * 0.4)
    = (0.2 * weight) – (0.08 * weight)
    = weight * (0.2 – 0.08)
    = weight * 0.12

    So, let’s get the carb factor:

    300 / TDD
    = 300 / (weight * 0.2)
    = 1500 / weight

    So, if all of our non-basal insulin is going to carbs, it means that:

    carb intake
    = carb ratio * carb insulin
    = carb ratio * non-basal insulin (ideally speaking)
    = (1500 / weight) * (weight * 0.12)
    = 1500 * 0.12
    = 180

    Therefore, everyone eats 180 grams of carbs no matter what they weigh.

    Heh. Math.

    1. Mark
      Mark May 1, 2012 at 6:38 am | | Reply

      These rules of thumb are not for you to solve for carb intake…so you can’t substitute here. They are only suitable for setting rates because they are empirical (trial and error – based on observations). In this case, the best I can offer is 180 is a carb constant (Y-intersection) for the rest of the math, but you are trying too hard (let it go).

  7. Jan
    Jan August 21, 2009 at 10:09 am | | Reply

    As the caretaker of a child with Type 1 (diagnosed at 8 and now 12 years of age), I find all formulas to be quite dangerous. Formulas can only be used as a general, ball park check. For first two years prior to puberty, my niece used 36 percent basal, the rest bolus. Now, in puberty, she is using 60 percent basal, 40 percent bolus. She is 85 pounds. Her Insulin Sensitivity Factor is 75 days, 110 midnight to 6am. This has been checked time and time again and verified by her Endo. I have John Walsh’s charts as a very loose reference (mostly to check basal per hour) and they are way off. Her lowest basal is .95. Her highest basal (which can go higher due to growth spurts), anywhere from 1.75 to 2.7 during the 6pm thru midnight hours. We get night basals almost every night and she wears the Dexcom 7 Plus cgms. Current Insulin to carb ratios are 1 to 7 breakfast, 1 to 13 lunch and dinner. All have been checked time and time again and are verified. We do fasting basals and skip meals to check basals all the time. The one thing you can check with absolute certainty are basal patterns. Unfortunately in teens these change very frequently. Very. Each person should do their own basal testing to determine basal need. Then they can figure out the rest. Forumulas such as these do not and cannot work for each person. Each person is an individual and needs may vary tremendously.

  8. kelly close
    kelly close August 22, 2009 at 10:52 pm | | Reply

    yes, it is DEFINITELY true everyone’s mileage varies on this! I found the changes really helpful though – even though my A1c has been under 7 for a long time, it wasn’t without a lot of hypoglycemia, so I think I’m nearly a much “higher quality” A1c, which isn’t really a term we hear a lot about. But wow to be at 5.6 Elizabeth – that is amazing! I wouldn’t change a thing either if I had few lows! And Lloyd that’s exactly what the educator said about my numbers – we had to change the basal first, which I hadn’t really realized, so I had long been “tweaking” the other formulas without getting the right basals. Thankfully I’m there now. That’s fascinating, Jen, about the 180 carbs – I think mine varies a ton, but usually around 160, so not too far off. Jan, if I implied anything BUT these are starting points, I’m so sorry. I think their point is the new formulas may be better starting points. I’ve also heard from a lot of diabetic friends that their current settings are the SAME as when they began pumping – probably many people could use tweaks, but the HCP teams don’t always spend time on it. As for a pump vs injections – I don’t think I could ever go back! I know all the math sounds insane, but you really only do it once and then tweak (but I hadn’t tweaked enough, that’s for sure!) And last, even though the reason my insurance pays for pumps and CGM is because I am in much better health with them, one of the nice bonuses about pumps and CGM is also that it is fewer pokes! Thanks Amy for the chance to guest post!

  9. T1 D
    T1 D August 23, 2009 at 3:54 pm | | Reply

    Yes, Jan, these are definitely BALLPARK FIGURES FOR ADULTS. THAT’S WHAT THEY ARE SUPPOSED TO BE!. AND Anon no, Anon, NOT everyone is supposed to eat 180 carbs everyday (no corrections in an ideal world !!!! ???? !!!! ARE YOU CRAZY ?????????? ).
    I eat 24 grm of carbs every day, not every meal BUT EVERY DAY and the correction NEW numbers are about right FOR ME.

  10. Cathy
    Cathy August 23, 2009 at 7:28 pm | | Reply

    I am the Mom of a 12 year old Type 1 girl and puberty is very difficult and not consistent at all. SOME if the CDE’s get caught into the formulas too much, although each family is different in their level of involvement and care.

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  12. landileigh
    landileigh August 27, 2009 at 11:46 am | | Reply

    i tried this, and I have been amazed at the drop in insulin I’ve had to take every day. the correction levels were totally adjusted for me, and I haven’t been above 160 since doing this! Thanks Kelly!

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  15. Jerry Nairn
    Jerry Nairn June 1, 2010 at 2:42 pm | | Reply

    Just packed so full of typos it is hard to get the formulas right. Could you re-edit this and correct them? Seriously. You used TTD over and over when you meant TDD, and there are other mistakes.

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