I’m coming up on week two of my Symlin experiment, and I’ve got to say: I love it.
Symlin, as you probably know, is a synthetic version of the human hormone amylin which — to quote the FDA — is “a naturally occurring neuroendocrine hormone synthesized by pancreatic beta cells that contributes to glucose control during the postprandial period.” Translation? It’s another hormone made by your pancreas (in addition to insulin) that helps control your blood sugar after you eat.
You don’t technically need amylin to stay alive, which explains why its role was discovered decades after insulin’s. But it turns out that when a non-diabetic person eats, their pancreas secretes amylin in patterns that closely mirror insulin. Check out this chart, courtesy of the FDA:
Turns out that amylin is like insulin’s wingman, helping to control blood sugar in at least three important ways:
-it slows down the rate at which your stomach empties food into your small intestine, which can prevent glucose spikes after meals. (It doesn’t, however, affect the amount of overall nutrients that are absorbed.)
-it stops your pancreas from releasing excess glucagon at mealtimes. This one’s a little confusing, so let me clarify: when you eat, the pancreas occasionally gets so excited by the presence of your bran muffin that it pumps out some extra glucagon, a hormone that triggers your liver to convert some of its stored glycogen into glucose and dump it into the blood stream. The result of this added glucose? Even higher blood sugars than the food itself would cause. I can’t help but feel like this is a little bit of overcompensation on the pancreas’s part (“I can’t make any insulin . . . but how about this other stuff?”) Regardless, excess glucagon screws up post-meal control, and tamping it down is a good thing.
-Lastly, amylin helps control your appetite. And, so the theory goes, the less you stuff down your throat at once, the easier post-meal control will be.
Sounds great, right? Well, there are a couple caveats. First, Symlin’s given by injection, adding yet another set of daily puncture wounds to your daily routine. It also can make you really nauseated, especially when you first start taking it. Lastly, and most importantly, it can result in severe hypoglycemia.
Let me explain a bit more on that point: Symlin slows your stomach’s emptying. So if you take your normal dose of a rapid-acting insulin like humalog, the insulin is likely to kick in before the food actually makes its way out of your stomach. That itself can be extremely dangerous. But making matters worse, you can’t just eat something to bring your sugar level back up, because — remember? — your stomach is stalled.
If the hypoglycemia isn’t severe, you can wait for a bit — once your stomach begins moving the food, your blood sugar will rise. But if it’s really low, or dropping, you need to take more drastic actions. Sucking on glucose tablets can help (to try to get the glucose to absorb through your mucous membranes). And it’s a good idea when you’re on Symlin to carry a vial of glucagon with you just in case.
However, I think a bit of this concern is overblown. Symlin itself does not lower your blood sugar; insulin does. Therefore, when you take Symlin, there are a couple easy steps to lower your hypoglycemia risk. First, delay your insulin dose (a square or dual wave bolus is great for this, pump users). Second, cut down your dose — experts recommend halving it to start and then working your way back up to an appropriate level. Do this, and in my experience, at least, you’ll minimize your risk of a disaster.
The flip side of Symlin, however, is that it can give you a bit of a false sense of security. You can eat a dinner of pasta with no noticeable effect on your blood sugar for one, two, three, even four hours. But when your stomach finally does empty, your blood sugar will rise. More gradually than had you not taken the Symlin, mind you, but it’ll trend upwards nonetheless. So you need to be sure to test more than just 2 hours after meals, and be aware that the rise can be higher (and occasionally more delayed) depending on how you react to certain foods. Case in point: last night I ate a small bowl of pasta at 7:15 and hovered happily around 120 until I went to bed. It was only when I examined the record of my CGM this morning that I noticed that I’d gone up to 185 for two hours around 1 in the morning, only to come back to normal by the time I woke up.
Next time: more about Symlin, including one of its pleasant side effects — weight loss.
For more information about Symlin in the meantime, check out the FDA’s description.