Mount Greylock weather update: A park ranger says the road over the mountain is currently closed due to snow. It may reopen tomorrow afternoon. Let’s hope the roads are dry by Sunday morning.
I had a nice run today. Well, the run was nice, though my blood glucose readings are still a major pain. If I exercise in the morning, no problem. But the afternoon is a different story.
It’s all about the insulin, people. In the morning, I usually don’t eat much before exercising, and I certainly haven’t given myself any insulin. But by the afternoon, I’ve eaten a couple times (at least) and I’ve taken some insulin to cover the food. Oh, that insulin-on-board! Obviously I can’t make the active insulin go away; it just hangs out in the blood stream waiting to lower my blood glucose. It keeps me alive, but it’s really crimping my style.
Let’s take a couple minutes to discuss insulin. Here’s the little bit that I do know.
- Insulin is an enzyme that is (normally) produced by the pancreas. It’s used to metabolize glucose in the cells.
- People with type 1 diabetes don’t produce any insulin, so we have to replace it by injection or pump.
- There are fast-acting, long-acting, and peakless insulins; but you only use fast-acting versions (like Humalog) in an insulin pump.
- The action profile of fast-acting insulin peaks quickly and has a tail of 4-6 hours.
- Insulin has a half-life. I don’t know how long it is, exactly; I’ve read anywhere from 26 minutes to 1 hour for Humalog. Anyway, it means the more you take, the longer it stays active (albeit with diminished power).
- Because insulin is injected/infused below the skin, it takes a little while to get to the cells in the rest of the body where it’s needed. But activity can make it absorb more quickly.
- If you don’t have enough insulin in your system, your body will convert fat into ketones, a kind of fatty acid.
When people without diabetes exercise, their muscles first use blood glucose (briefly) and muscle glycogen. (Glycogen is a kind of simple sugar stored in muscles.) After about 15 minutes, insulin levels drop, and the body switches over to burning fat predominantly. The rule-of-thumb for people without diabetes is to consume 1 gram of carbohydrate for every minute after the first 45 minutes of exercise.
What’s the right balance between active insulin, basal insulin, food, and exercise? I’ve been trying to emulate as much of this “normal people behavior” when I exercise. I try not to bolus for about four hours before going for a run or ride, and I lower my basal insulin by about 50-60%, starting about an hour beforehand. This should reduce the amount of insulin in my bloodstream that could lower my blood sugar. And I eat a little something right before exercising to try to prevent a dip. So far, the right balance is elusive.
I have been recording a lot of data over the last month using a special logbook, which I’ll show another day. But here’s what I did today — just remember it didn’t work as well as I’d hoped.
12:44 - Bolus 4.4u for lunch 13:25 - Bolus 2.7u for "Friday cookies" 15:45 - 204 mg/dL 15:45 - Start temp basal of 0.2 u/hr 16:30 - 15 gm of carbs (sports drink) 16:50 - 279 16:50 to 18:37 - Ran 5.5 miles 17:40 - 86
Obviously, my pre-exercise readings are not great. I’m not embarrassed to show them here, though they certainly aren’t what I’d like. Managing diabetes is all about living with the unpredictable and experimenting until you find what works, and then you turn it into a habit. My big goal is to be able to start exercising with a reading below 150 mg/dL and finish above 100. Today I started at 279 and ended at 88. Tomorrow I’ll try something new and get closer to what works.
Update: Five months later, I’ve learned a lot.
