Stacking strikes again

When I first went on insulin about 15 years ago, I was warned that in a sense I was given a loaded gun that could indeed kill me. Experts say that high blood sugar takes a long time to do us in while VERY low BG can terminate life very quickly. Understanding these facts has enabled me to be an effective insulin user—at least most of the time.
Last Monday, my wife and I decided to take a half day of vacation and visit our neighboring town of Great Barrington. We set out that day to explore the town as if we were tourists.
My BG at noon was 263 so I pumped 5 units of Novolog since each unit lowers my blood sugar about 30 points. When we stopped for lunch about 45 minutes later, I tested again and my sugar reading was 173. The wizard in my Medtronic pump helped me determine the correct amount of insulin to cover the estimated 50 units of carbohydrates I was about to consume. I pumped 6.25 units of insulin. Given that I still had several units of active insulin in my body, the additional units set me up for a low. This approach to BG management is called stacking, meaning that one bolus of insulin was stacked on top of another…my bad.
As you can see in the graphic of my log book below, at 3:50 PM my blood sugar was 47 and I had all of the low BG symptoms (blurred vision and sweaty body). I consumed about 25 grams of carbs to bring my sugar back up and about an hour later my BG was 96. The lesson of course is to avoid stacking. Although my sugar returned to the normal range, I experienced the residual effects of going low—fatigue and a feeling like I’d been run over by a truck—always unpleasant.
My advice is to respect the power of insulin and just like a loaded gun, it must we used with care.
Diabetes log book