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  • my DIY OGTT

    I have read up on Kraft survey for some time (Ivor Cummins, John L., Dr Brewer, Meridian Valley, even Dr Kraft himself). Convinced it is an appropriate tool for IR assessment. My only concern is I follow a low carb diet (~50g/day). I've posted before about this concern. Typical recommendation is to "carb up" fro 3 days: eat at 150g carbs/day for 3 days prior to taste. Dr Kraft mentions the need for a 14-day carb-up. I questioned the effectiveness of the 3-day guidance, so I did an experiment.

    1. I researched home glucometers. Bayer Contour Next tops most lists for accuracy, so I bought one.
    2. I had a large bag of Now Dextrose (chemically identical to glucose) on hand, so I had a simple 75g glucose challenge source available.
    3. Chose a simple experiment with a control: (a) typical low carb diet prep, then do DIY OGTT, (b) 3-day >150g carb/day prep, then repeat DIY OGTT
    4. DIY OGTT: overnight fast, baseline glucose reading, 75g glucose challenge, follow up glucose readings at 30, 60 & 120 min PP (post-prandial)

    I wish I could paste in plots, but textual data is pasted below.

    Low Carb Prep
    Status, min PP Glucose [mg/dL]
    0 99
    30 192
    60 148
    120 90
    3-day High Crab Prep
    Status, min PP Glucose [mg/dL]
    0 107
    30 193
    60 136
    120 106

    "Oatmeal OGTT" (eat "healthy" plain oatmeal & take same data
    Status, min PP Glucose [mg/dL]
    0 107
    30 153
    60 144
    120 117
    Other data
    1. waking glucose after 11 hour fast = 117
    2. 70 min PP after low carb breakfast (3 eggs cooked in butter, veg, cheese, coffee), glucose = 107
    3. 60 min PP after low carb dinner, glucose = 99

    1. 3-day high carb had no significant effect -- nearly identical blood glucose response. I see no reason to do the 3-day high carb prep unless there are other considerations..
    2. I was not surprised that oatmeal causes a nasty blood glucose spike. There are better ways to get fiber without the sugar.

    1. Is it possible to get an accurate Kraft test result if you follow a low carb diet?

  • #2
    Thanks cyclist, I've wondered about the efficacy of an OGTT for very low carb KETO and carnivore adherents.


    • #3
      The 2020 KETO Summit was this weekend in Denver... here's a good related talk.


      • #4
        Interesting experiment. Thanks for posting.
        Here are my profiles over time with no planned carb loading.
        I was surprised at the variation.
        Not sure is you can assume the same baseline in your experiment.

        At 13:20 here


        • #5
          Hi Gerry,

          Thanks for weighing in. I had only watched about 5 min of your video before I posted. I have since watched the entire presentation, which is excellent!. I thought to myself, "Gerry sounds like an engineer." I see this is true from your comments. Me too.

          I agree. More tests with/without carb-loading would improve the validity of my experiment. I am more inclined to repeat no carb-load DIY OGTTs, however. I'd actually rather start doing something about my suspected insulin resistance beyond a low carb diet.

          My biggest concern is a compromised Kraft test result due to my low carb diet. I still don't have a good feel for that.

          I landed here from Wheatbelly (also low carb & pro-CAC tracking). That approach worked for a while, then it didn't as I got older (57 now). CAC every few years and rising.

          I am not fully convinced yet of the "CAC increase is good due to plaque stabilization" thinking. It's a reasonable hypothesis supported by Dr Brewer's anecdotal evidence, but it does oppose the basic thinking on which CAC was derived: that hard plaque is 20% of total plaque burden, which indicates any increase is a bad trend. Not sure how this get resolved.

          Were your OGTT results based on lab blood draws or home glucometer tests?