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The Diabetes Phenomena

We’ve all heard the saying in jest about “practicing medicine“. Some people remark that they feel like their provider is “practicing“ on them.  We know that diabetes, in particular, is part science and part art.  If we gave 10 people the same meal and they took the same amount of insulin, they would likely get 10 different results. Diabetes management feels like a lot of trial and error.  And I often say, every meal is a chance for a do-over.

Over the past 25 years of providing diabetes care and education, I have noticed some interesting patterns in working with individuals taking insulin.  If you look up the word phenomenon in the dictionary, one definition is “a situation that is observed to exist or happen, especially one whose cause or explanation is in question”.

You may have heard of the “dawn phenomenon” which is a rise in blood glucose in pre-dawn hours due to increased growth hormone and cortisol production. This is widely known, and many individuals make insulin adjustments to account for it.


During my years of looking at blood glucose and food records, my colleagues and I decided to grant some other mysterious causes of high glucose as their own “phenomenon”. Let’s see if you can relate to any of these:

  • “Coffee phenomenon” (most any caffeine) – A rise in glucose after drinking coffee (including black) (due to ? adrenaline perhaps?)
  • “Cereal phenomenon” – A rise in glucose seen by patients consuming cereal which requires a lower carbohydrate to insulin ratio (more insulin) than other meals with the same carb amount.
  • “Shower phenomenon” – An unexplained increase in glucose when tested before and after showering. If wearing a pump and disconnecting for a long shower or bath, a small amount of insulin may need to be replaced.
  • “Bubble-in-the-infusion-set-tubing phenomenon” – Air bubbles in the tubing of an insulin pump infusion set should be removed by disconnecting and priming the air out.  Also, when the infusion set is disconnected for showering, etc. gravity may cause the insulin to back-up into the tubing leaving a small air bubble.  Holding the pump higher than the infusion site when reconnecting or re-priming the tubing will avoid these bubbles.
  • “New infusion site phenomenon” – When new infusion sets are inserted, they are usually primed to the end of the plastic cannula / catheter (some pump sets require a separate priming bolus to be delivered and some don’t).  If you don’t change your infusion set before a meal, which is recommended, it may take some time for the basal insulin to make its way through your tissue and into your bloodstream.  We sometimes refer to this as a lag time.  You can try to avoid it by taking a food bolus after changing your site or leaving your old site (or pod) attached to your body for an hour or so to let the last drops of insulin below the skin to absorb.  You may discover that using a slightly larger priming bolus (+ 0.1-0.3) than the one specified for your cannula length helps but is not enough to cause a low.  The typical priming amounts are 6mm-0.3, 9mm-0.5, 13mm-0.7 and 17mm-1.0 units.  See your package for the specific amount recommended.
  • “Nap phenomenon” – These highs may be just from not moving around physically – can also be seen when being a couch potato.
  • “Food on the fingers phenomenon” – If testing with a fingerstick meter, a high glucose can occur from residual food or if glucose tabs were eaten to treat a low glucose (wash hands or wipe off the first drop of blood if unable to wash hands).
  • “Chinese food or pizza phenomenon” – a delayed high glucose from a meal high in fat, which causes insulin resistance and delayed digestion so it may require more insulin and a split dose.
  • “Bad insulin phenomenon” – Empirically, high glucose occurs when insulin denatures if exposed to moderate to extreme temperatures (i.e. using a mail-order pharmacy, traveling with insulin, having it freeze in a hotel room refrigerator, or a lot of agitation).
  • “High after exercise phenomenon” – You may think, “If exercise is supposed to lower glucose, why am I am rising afterward?  When you are moving around physically, it is the only time that glucose can go into a cell without insulin to facilitate it.  As soon as you STOP moving, glucose in the bloodstream stops passing freely into muscles and takes time to go back into storage, so there may be a temporary rise.

It’s easy to get mad, disappointed, and frustrated with diabetes several times a day but that can be stressful – and stress will raise your blood sugar more! I think it is better to figure out what is happening with your diabetes if you approach every situation that doesn’t go exactly as planned like a scavenger hunt. In other words, look for some clues. All of a sudden, those unexplained phemomena become explained!

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