SUGAR SURFING LESSON: BASAL NEUTRALITY
The ability to establish and keep a steady basal blood sugar trendline pattern (called a “shelf” in Sugar Surfing™ parlance) is an essential step in mastering the art of Dynamic Diabetes Management. Establishing a steady basal insulin effect (i.e., basal neutrality) is vital to long term Sugar Surfing success.
Basal insulin, whether delivered by an injection or an insulin pump, has a single purpose: to maintain blood sugar stability over time. It is not intended to lower blood sugar levels, although many doctors and patients use it for that reason. And as I describe in the book Sugar Surfing, basal insulin delivery CAN be modified to slowly correct out of range blood sugar levels. This can be especially helpful in children. Cutting back on basal insulin delivery via a pump can also be used to slow a downward drifting blood sugar level (i.e., “Engine Brake”).
When blood sugar levels are in balance, the amount of sugar (glucose) LEAVING the bloodstream is matched by glucose ENTERING the bloodstream. There is always going to be some amount of back and forth in the blood sugar level even in persons without diabetes. Therefore, a reasonable definition of what constitutes “steady” is needed. I have used a blood sugar trendline which remains within a “width” of 30 mg/dL [~ 2 mmol/L] over at least 1 hour as worthy of the title “glycemic shelf”. Feel free to apply your own spin on this term, but don’t make the width of the shelf too wide or too narrow.
If, as they say the “proof is in the pudding”, then if basal insulin provides steady trending at any glycemic level, it can be argued that basal insulin delivery is properly set or dosed. How does this get validated? In the absence of major forces which would push BG trending up or down (e.g., food, stress, exercise, illness, certain meds), a steady glycemic shelf validates a reasonable basal insulin delivery.
It’s known that daily basal insulin doses and rates tend to be “heavier” than needed in many people taking insulin. In a minority of cases, basal insulin is too “light”. The Sugar Surfer’s goal is to achieve net basal neutrality (on average, over time measured in days or weeks; not just on a single day). What defines these states (basal heavy and basal light) can be seen in the tendency of the blood sugar to generally drift upwards after meal time insulin has worn off (when basal light). The opposite is seen in basal heavy individuals. These trends need to be consistent. Even a basal heavy individual will have upward BG drift patterns sometimes and basal light persons may have a drop every now and then. But in general, the tendency will be to drop BG levels between meals in basal heavy users and vice versa with the basal light groups.
If there are elements of both heavy and light embedded in an insulin pump basal rate profile, then the result may be significant blood sugar “rollercoastering”. Aim to keep basal rates to a minimum.
Testing your basal insulin requires careful conditions to be set up. Most of the time you’re testing basal delivery overnight, assuming no snacks are being consumed and you are sleeping well. It also means that you didn’t eat a large carb-laden meal late in the evening which is taking longer to digest due to the additional fat and protein in the meal. It also means you didn’t spend the prior day involved with an extraordinary amount of physical activity or exercise. It also means you are not sick or unusually stressed.
Setting those exclusionary situations aside, once you fall asleep, if the basal insulin is set properly you will tend to trend a BG on a shelf through the rest of the night…ON AVERAGE. Exceptions will happen, but if most of nights you trend straight, your basal insulin is relatively set well.
Some people may have glycemic surges (delta waves) or drops overnight or in the early morning. If these are proven to be consistent occurrences, the basal insulin can be adjusted (if using a pump) to offset these surges (or drops). How to do that is a different lesson. But in many patients, fewer basal rates on a pump are better than many. Many of my patients use a single rate quite effectively. Resist making basal rate changes on just a few days of data (or one).
During the day, testing a basal rate or injected dose involves controlling the forces which would alter the BG trending. That means withholding food or snacks, not engaging in strenuous activity and not testing this during illness, stress or if taking medications known to affect blood sugar levels. If these are controlled or curtailed, and is the BG trends steady on a shelf, then this serves to validate basal insulin delivery over that period of observation. Test the day in segments (overnight, morning, afternoon and evening) and do these “tests” when you have the time and opportunity. It might take a few weeks to figure this out, but it’s time well spent.