10 Responses

  1. Sara
    Sara January 25, 2014 at 5:13 am | | Reply


  2. Jay Kauffman
    Jay Kauffman January 25, 2014 at 6:17 am | | Reply

    hypo-cashemia. Love it. Now I’m wondering if you could apply the insulin metaphor in reverse to our economic system and see if any brilliant new insights arise.

  3. Mike Ratrie
    Mike Ratrie January 25, 2014 at 7:28 am | | Reply

    Wil, that was a pretty awesome bit of writing! Just mind your “It’s” and “Its” ;)

    1. Wil
      Wil January 25, 2014 at 8:35 am | | Reply

      Must have been a case of typo-glycemia! :-)

  4. Scott K. Johnson
    Scott K. Johnson January 25, 2014 at 8:24 pm | | Reply

    Fantastic post, Wil (as usual)! Makes so much sense when we look at it this way.

  5. Katie
    Katie January 25, 2014 at 9:16 pm | | Reply

    I love everything you write.

  6. Terry Keelan
    Terry Keelan January 26, 2014 at 5:56 pm | | Reply

    Typo-glycemia. there was an audible moan from my computer when that term scrolled onto the screen.

    Well done.

  7. Scott Leibrand
    Scott Leibrand January 28, 2014 at 3:22 pm | | Reply

    First off, good job turning something prosaic into something poetic. Seems like a lot of people really appreciate the metaphors to help understand some of the basics of insulin activity. But I don’t think you completely answered Susan’s question, and I’m not sure that what you did say is the whole story. Here’s a bit more to explore the physiological impacts of early and late boluses.

    As you helpfully point out, insulin doesn’t simply neutralize carbs: it up-regulates the absorption of glucose from the blood by the body, which reduces BG over time. You are also correct to point out that if you start the insulin too early, the removal of glucose from the blood starts earlier than the addition of blood glucose from the meal, and the inverse occurs if you bolus late. Since the two processes are both happening not-quite-simultaneously, you end up with a persistently low BG for an early bolus, and a persistently high BG for a late one.

    However, it’s important to note that the initial effect does not persist indefinitely, and that there are physiological effects counteracting it. In addition to being proportional to insulin activity levels, the speed that glucose is removed from the blood is also a (sub-linear) function of the actual level of blood glucose. This means that when BG is low, less glucose is absorbed over the time the insulin is active, and conversely, when BG is high, more is absorbed. In addition, there are other regulatory effects that cause the liver, for example, to dump glucose into the bloodstream when BG levels are too low.

    The result of these effects is what is commonly referred to as a “rebound” or a “crash” in many cases. In particular, when you treat the low blood sugar caused by an early bolus (with additional carbs or a lower temp basal), you are likely to see a rebound effect as soon as all the carbs are absorbed by your small intestine into your bloodstream (which can be 3-4 hours after a large meal, depending on your absorption rate of carbs). Similarly, when you treat the high blood sugar caused by a late bolus with additional insulin, then once all your mealtime carbs are absorbed, you still often have some insulin onboard that can cause you to end up with lower blood sugar (a “crash”) than if your bolus had been timed perfectly. But even without extra correction, the physiology (glucose activity being a function of BG levels) indicates that a perfectly sized bolus can cause a long low followed by a rebound if taken too early; or a long high followed by a crash if taken too late.

    Because there are so many physiological factors interacting to effect BG levels, it is important to be aware of how much insulin is still on board and still active, *and* how long it takes for your body to absorb all ingested carbs as glucose into the bloodstream, particularly from large meals. But more importantly, continue checking BG levels appropriately after a meal (ideally with a CGM when possible), particularly if you have experienced post-meal rebounds or crashes.

  8. Faith
    Faith May 29, 2014 at 2:41 am | | Reply

    Thanks for this great thread. I’ve found that taking my bolus 15-20 minutes before eating helps tremendously. My food tends to digest before insulin peaks, otherwise. It is scary taking the insulin this early, because it could cause a low depending on what I’ve eaten. Understanding how complicated the digestive process is really gives me greater appreciation for how amazing our bodies are.

  9. Anna
    Anna July 7, 2014 at 9:48 am | | Reply

    I still don’t get it.

    If I bolus for 50 carbs, but let’s say 10g of carbs is absorbed into my blood stream and raises my blood sugar before insulin takes effect, well then I have a high blood sugar+ now 40g of sugar, but still insulin for 50g of carbs. SO, doesn’t this mean that the 10g bolus of extra insulin on board, that now won’t be needed for what remains to be absorbed (40g) should now work to lower the high BS? Basically that the bolus, turns into a correcting dose?

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