When I was first diagnosed with diabetes, I really only had one pressing question: what would I do if I was marooned on a desert island? I’m insulin dependent, and if I don’t get insulin, my cells won’t be able to eat, my blood sugars will rise, and I’ll either starve or go into a coma. Granted, I don’t intend to ever be without insulin, but if it happened, what would I do? Could I change my diet and keep my blood sugar in a healthy range for longer? Exercise more to keep my blood sugar down? Manufacture my own insulin with out of blended rat pancreases spun down in an improvised centrifuge made of sisal twine and coconut husks? What would MacGyver do?
So then I got an idea–I could get some answers about how my body responds to insulin, and food in general, by fasting and measuring my blood glucose frequently. I could design little mini-experiments to isolate certain aspects of my endocrine system and get pretty good results. When I learned that my endocrinologist has a program where he lends out continuous glucose monitors that stick into me for three days and measure my blood sugar every five minutes, I decided to use those for my experiments.
I just started my fast and continuous glucose meter today. There’s three main phases of my experiment: measuring my basal insulin response, measuring what my body does without any insulin, and comparing the effectiveness my insulin pump to traditional needle-delivered insulin.
For the first day, I’m going to inject myself with my normal dose of basal insulin. Basal insulin is a slow-release insulin that works at a constant rate over 24 hours. It’s used to signal my cells to eat the small amounts of glucose my body produces even when I don’t eat anything. Watching my blood sugar change with a fixed amount of basal insulin in my system will tell me how well matched my basal insulin is to my body’s glucose production, and how that varies during the day as my body produces more or less glucose.
For the second day, I’m not going to inject myself with any insulin. My basal insulin should wear off within ~30 hours of my first injection, and my blood sugar should start to rise, as my body produces small amounts of glucose. I’m interested to see the rate at which my body produces glucose. This is a more direct measurement of the rate than on the first day, as there’s no mechanism(insulin) reducing the glucose concentration. I’ll let my blood glucose rise up to 250mg/dL (the threshhold for diabetic ketoacidosis, but one I’ve crossed a number of times accidentally), at which point I’ll put on a pump and give myself rapid-acting insulin to bring my blood glucose back down to my normal 100mg/dL.
On the third day, I’ll run the basal drip from the pump, which has an elevated basal drip between midnight and 6am. The elevated drip is intended to account for the dawn phenomenon, where growth hormones released in my sleep inhibit insulin, causing a rise in blood glucose. By increasing my basal drip, I try to keep my blood sugar constant while the growth hormones are being released. Watching my blood glucose change will help me understand how well matched my basal pattern is to my body’s glucose production and other hormonal activity.
Fasting is a little tricky for diabetics. Our sensitivity to insulin increases when we don’t eat, and without eating, we can’t bring our blood sugar back up if it goes low. I decided to set some baselines: For this test, I’ll keep my blood sugar between the range of 50mg/dL and 250 mg/dL. 50mg/dL is the point at which my thought processes and coordination get affected by my lack of blood sugar, and I’d eat a piece of hard candy if I got to that point, enough to bring my sugar up to my normal 100mg/dL target. 250 mg/dL is the point where I start to be at risk for diabetic ketoacidosis, a potentially dangerous side effect of high blood sugar and low insulin. I’ve had my blood sugar accidentally go to that level before, even overnight (and one for well over a month, before I was diagnosed), so I don’t believe I’m taking an undue risk. If my blood sugar gets that high, I’ll give myself rapid-acting insulin to bring it down. Because I’m not eating anything for the next three days, I don’t expect any rapid changes in blood glucose, and as long as I monitor it regularly, I don’t think this is a risky experiment.
I’m also very curious about fasting in general. I’ve never fasted more than one day for Yom Kippur, and I’ve heard lots of good things about fasting improving health, alertness and self-awareness, and I want to experience it for myself. It also sounds kind of hard, to not eat for three days, so I figure it’ll be an exercise in self-control and insulin calculation. Let’s see how it goes!
