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Thread: Rule of thumb/formula for different I:C ratios?

  1. #1
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    Default Rule of thumb/formula for different I:C ratios?

    Are there any guides/rules of thumb/formulae for the difference between I:C ratios someone might have?

    I know there are for calculating ISF (i.e., dividing 1600, 1700, etc. by TDD) and know there are for calculating carb ratios, but is there any rule of thumb for how much two carb ratios would be expected to vary?

    The reason I ask is that DD's breakfast carb ratio is 1:30, while all other meals and snacks are 1:50. The CDE mentioned that that seemed like a "big" difference. We suspect that it might be masking a basal issue. For now, DD is in school, what we have seems to be working, and weekends are different enough from school days not to provide a useful guide.

    Just wondered.

    TIA
    virgo39
    DD dx at 5 yrs, 3 months (11/09)
    Omnipod w/Novolog (7/10)

  2. #2
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    Quote Originally Posted by virgo39 View Post
    Are there any guides/rules of thumb/formulae for the difference between I:C ratios someone might have?

    I know there are for calculating ISF (i.e., dividing 1600, 1700, etc. by TDD) and know there are for calculating carb ratios, but is there any rule of thumb for how much two carb ratios would be expected to vary?

    The reason I ask is that DD's breakfast carb ratio is 1:30, while all other meals and snacks are 1:50. The CDE mentioned that that seemed like a "big" difference. We suspect that it might be masking a basal issue. For now, DD is in school, what we have seems to be working, and weekends are different enough from school days not to provide a useful guide.

    Just wondered.

    TIA
    No, there's no formula I'm aware of for calculating deifferent carb ratios for different meals.

    The general formula used the 500 Rule, which is that dividing 500 by TDD will give you your "average" carb ratio.

    For example for DD who's on 20 units a day, the 500 Rule suggests that her carb ratio is:
    500/20=25, ie. 1 unit covering 25 g of carbs.

    Question for you - are your current ratios working? If so, I'd never mind the CDE and let them keep working..
    ________________________________________
    Wilf

    Proud Dad of Amy (18), diagnosed Aug. 2006 and getting MDI of Apidra and Lantus..
    and Sylvie (13); very happy husband of Shirla!

  3. #3
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    Quote Originally Posted by wilf View Post
    Question for you - are your current ratios working? If so, I'd never mind the CDE and let them keep working..
    They do seem to be working okay. The CDE and I did agree to a "if it ain't broke, don't fix it approach", I was just curious.

    I do find knowing what the various formulae are kind of helpful ... DD's numbers don't necessarily correlate with all of them, but they can be useful in identifying where I might start if I wanted to make a change, kwim?
    virgo39
    DD dx at 5 yrs, 3 months (11/09)
    Omnipod w/Novolog (7/10)

  4. #4
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    My DD's breakfast ratio is also much different then her dinner ratio. The endo wasn't too concerned because it worked. He said its not unusual to have such a disparity between morning and evening meals.
    Wendy

    Walking to Cure on November 2nd, 2013!

    [FONT="Comic Sans MS"][COLOR="Purple"]Mom to McKenna, 13 years old, dx'd 12/7/09 (9 yrs);
    7/6/10; PINGing with Novolog

  5. #5

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    we use a 400 rule for I/C

    not sure what rule or equation for different meals.

    hope you find the answer!
    Sheri
    Daughter dx~ age 12

    Amber ~age 17 Pumping w Ping
    Novolog

    Faith, Hope, and Love ~
    the greatest of these is Love.

  6. #6
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    We don't use a handy dandy formula ... we just see where we are about 2 hours after, using CGM ... and let that guide what the I:C ratio should be going forward.

    Our ratios are vastly different depending on her level of activity ... for example if she is in school, out of school, a soccer morning, etc.
    Lisa

    Mom to:
    Maddie 12 (dx 3/09) T-Slim Pump-Dexcom CGM
    Riley 12 Twin Brother to Maddie (non-d)

  7. #7
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    I'd go with what Wilf said. If it's working, there's no need to fix it. A lot of people are more insulin-resistant in the morning.
    ~Ivy
    Mommy to 3 princesses & 1 prince
    ~K (dd3) diagnosed 4/17/10 at 6 years 4 months.
    Pink MM 722 Nov. 24, '10 w/ novolog
    Pink MM 523 April 22, '11 w/ novolog
    Dexcom -- sometimes

    "And we know that all things work together for good to them that love God, to them who are the called according to his purpose." Rom. 8:28

  8. #8
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    I don't think it's unusual for some people to need almost twice as much insulin for boluses as other parts of the day. For example, many people are very insulin resistant in the morning due to hormones (especially children and teenagers). Excess hormones can cause insulin resistance, and therefore, you need much more insulin to counteract that.

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