Calculating for Smooth-Sailing With Insulin

T1 sailor Erin Spineto shares the longform math she does to get through a day on the water without a low.



IslandsAndInsulin_300pxIn her book Islands and Insulin: A Diabetic Sailor’s Memoir, T1 author Erin Spineto chronicles her quest to sail solo around the Florida Keys and lose her fear of her diabetes. This excerpt from that memoir takes place as she is training for the journey:

24 November 2009
Seal Beach, CA

If you have ever had the unusual pleasure of spending time with a diabetic, you might have noticed a moment when they look off to the left and appear absorbed by thoughts somehow not entirely related to the current conversation. If you wondered what was running around in their head, here is a glimpse into the things they think about on an almost constant basis:

I am heading out to Catalina Island today for my shakedown cruise with Frank and three of his other students. It will be my opportunity to prepare more for my Florida trip. At 05:30 my blood sugar is elevated to 241. My formula for correcting this is to use 1 unit of Apidra insulin for every 50 mg/dl that my blood sugar is above 100. So 240 minus 100=140. Divide that by 50 and you get 2.8 units.

I push the insulin and continue calculating. I have been battling bronchitis for 5 days. The extra bacteria will send my sugars higher than usual. I haven’t worked out in 5 days, so my body will not be as sensitive to the insulin until I get in 2 to 3 good workouts. Driving in the morning will also send my blood sugars higher because I will be inactive at a time that is hardest for me to control my blood sugars. All of this means higher insulin needs.

My basal rate needs to be raised. It’s programmed into the insulin pump with different rates for different time periods during the day. It has a program that will increase or decrease this amount by percentages if my situation varies from a typical day.

I would have changed it to 120% of normal to accommodate for my illness, and probably an additional 15% to 20% for the car ride, so I decide on a total of 145%. If I increase my basal rates too much, my blood sugar will crash, so I am conservative with the estimate. But having high blood sugars on a trip doesn’t sound too good, either. It will usually make me groggy and slightly nauseous.

With these calculations running through my head, Shea, Eli, and I arrive at my parents’ house in Seal Beach by 06:30. I drop off the kids and head out for a few moments to get a bite and clear my head. I hit Jack-in-the-Box for a soda and walk across the street to Starbucks for a breakfast sandwich. (Caffeine blasphemy, I know, to bring soda to Starbucks, but I just can’t get into the whole coffee thing.)

Another blood sugar test shows 286. The last insulin correction was an hour and a half ago, so it’s halfway done with its job, which should have put me at 160. 286 – 160 = 126 higher than I wanted to be. Divide that by 50 gives 2.5, but I don’t want to overdo it, so I pump in 2.0 more units for the high blood sugar and 1.5 for the breakfast sandwich.

(I skip the Symlin, an injectable medicine that reduces the post-meal blood sugar spike, because it can make me nauseated and no one needs that kind of help when they’re about to get on a boat.)

With my belly full, I make the short drive to the boat. The air is crisp. A perfect Southern California fall day. Anticipation of spending a day like this on the water puts a spring in my step as I drag my bags down the dock to the boat. We get underway at 10:00 a.m., after another blood sugar check.

361. That’s crappy, and requires another correction. 361 minus 100 and divided by 50 gives me 5.2 units. Sitting on this boat motionless is going to raise my blood sugar even more, so I increase my temporary basal to 155% and try to focus on sailing.

Most of the morning is spent trying to get my sugars down. Time and time again I up my basal and correct even more. I manage to bring it down to the two hundreds by lunch, but it doesn’t get much better than that. We anchor that afternoon and, after a quick swim in the surprisingly warm water, we hike across the isthmus to watch the sun set over the pacific side of the island.

The walk couldn’t have been more welcome; a chance to stretch my legs and get my body more sensitive to the insulin. It causes my sugar to drop into the good zone, and then keeps going down. It ends up at 42, just 12 points away from the level at which my doctors told me I would pass out.

The PowerGels I keep in my pocket while sailing bring my sugars right back to normal. They provide a dose of sugar engineered to get into my system quickly, and they come in a handy little package that makes them easy to keep on hand.

Tonight as I slip into the forward berth on our boat, I keep my CGM close in case it wants to wake me with the news of an impending low. In the morning, I recalculate my basals and boluses. My confidence has built up and I am ready to push harder to achieve better numbers while on board.

During the weekend my brain is constantly wracked with math and strategies and analysis of every variable to make the best attempt to keep my blood sugars stable. The other crew members simply enjoy the sea and the sun and let their pancreases do all that hard work for them.

So, next time you see your diabetic friend start to go to that place where they stop listening to you for a brief moment, pause, just for a second, to give them a chance to zip through the math, and then go ahead and finish the story. They’ll appreciate the gesture.

You can purchase the memoir Islands and Insulin: A Diabetic Sailor’s Memoir at http://www.islandsandinsulin.com/.

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