Sugar Surfing Lesson #6: The Basic Pivot
The pivot is to the Sugar Surfer as the forehand or backhand is to the tennis player. In this lesson I will review the basic insulin pivot. All the basic anatomical structures are displayed or highlighted in the images below. Units of measure in the upper picture are expressed in mg/dL and in the bottom image the units are mmol/L.
From left to right, the following six core Sugar Surfing™ structures are visible: a delta wave, pivot, lag time, drop, inflection and shelf. The effective duration of insulin action is also shown (blue bracket). This is a classic insulin pivot. Carb pivoting will be reviewed in a future lesson.
The decision to create an insulin pivot must be made by the person. In this example it was decided that an upward trending blood sugar level at the level shown was worthy of a change in direction. Had the threshold glucose level been lower, then a smaller pivot could have been attempted.
Sugar Surfing is 'management in the moment'. This particular "moment" involved the discovery of an upward trending blood sugar at 4AM. The evening before was characterized by an in-range glycemic shelf created by two I-chains following a meal composed of a sirloin steak plus some slow digesting carbohydrate side dishes. This delta wave occurred after going to sleep. It was not due to an inadequate injected basal insulin dose or basal rate.
Some insulin pumping Surfers may choose to prevent delta waves with temporary basal rates or extended boluses (a calculated rapid-acting insulin dose delivered evenly over several hours via pump). This is a legitimate move and like other Surfing moves takes time and practice to get the best results. I will not discuss it any further in this post.
The pivot dose selected was based on prior experiences. This is described in prior posts and the book Sugar Surfing. Briefly, you can start with whatever dose would be generated by applying a standard correction factor calculation to reach a 'target' blood sugar level (you choose the target and divide the difference between actual and target with your correction factor). Understand that the dose you first calculate might be underpowered, but it helps you get a safer assessment of what range of rapid-acting insulin doses to use in these situations.
After about 20 minutes from injection (or simple bolus) time (the lag), the drop starts (actually an exaggerated inflection). After around 2 hours another inflection occurs. This inflection indicates when the prior pivoting dose lost most of it's glucose lowering effect. Please note that the time from the injection (simple bolus) to the second inflection represents the effective duration of insulin effect. In this case, it was approximately 2 hours. After the infection, a shelf (period of relative blood sugar trending stability) extends for the next hour.
One of the first maneuvers new Sugar Surfers attempt is the pivot. Not all pivots result in as clean a landing as the one shown here. A partially effective pivot will often deflect a rising blood sugar trend. Sometimes an attempted pivot will only to stop the rise and turn the trend into a new, albeit higher, glycemic shelf. In both cases a second pivot (or drop) dose can be considered after a reasonable waiting period. Once you can interpret inflection points and their relationship to insulin action, you will be able to more boldly dose follow up pivot doses. I have discussed "double tap" pivoting before.
Ok Surfers! Hit the beach!