Tuesday, March 13, 2012

The Bell Curve of Digestion

Digestive systems are funny things. They grumble, they gurgle, and they have their own little routines just like everything else.

I don't know about you but my digestive system is so routinized that, if I somehow lost the ability to understand or remember what week of the month it is, I could always figure it out based on how it is behaving. It has its own fun little cycle that is closely tied to my water retention, weight gain, crampy mood swing cycle.

And don't worry, that's as much detail as you're going to get about THAT...today anyway.

Digestion, or at least my digestion rate, also wreaks havoc on my blood sugars.  It took me a while to figure that out because what happens (to me at least) feels very counter-intuitive.

For me, the problems start when I eat a big meal.

With a normal meal I can count the carbs, take my insulin, eat and expect my sugar (if I calculated the carbs properly AND there are no other variables in play such as exercise, illness or periods) to climb up and then fall back down to 11-12 (mmol/L) within about two hours and back down to 6-7 within three. If you wanted to draw it, it would look like a pretty little bell curve.

With a larger meal, it takes longer to digest the food so that nice little bell curve of blood sugar activity starts to look more like an upside down curve.

Instead of my blood sugar climbing, peaking and then dropping back down again - what I've discovered is that my blood sugar drops first, quite significantly, and then climbs a few hours after it should.

Here's what happened on Saturday night when we went out for Mexican food. There are lots of numbers so hopefully I don't confuse anyone...

I was 6.3 before dinner. I ate nachos with guacamole, a chorizo flauta (sausage meat and potatoes in an egg-roll type cover) and then a quesadilla. Lots of carbs, lots of cheese and other high fat things to mess up digestive efficiency.

An hour after dinner, we decided to have dessert. I checked my blood sugar - it should have been about 15 by then. It was 5.2.

On a normal night that would be cause for panic because, if I'm 5.2 that soon after eating, I'm only going to keep dropping thanks to the pile of insulin that's still floating around in my system. But, because I had such a big meal (and because I've been through this before and learned the hard way) I knew that I still had a lot of digesting to do.  Within an hour or so, my blood sugar was going to start to climb.

I had a piece of cake but did not take ANY insulin for it. I figured I'd wait another hour to see what was happening before tossing more insulin into the mix.

An hour after having cake, and now two hours after having a huge meal, I was 5.0.

My brain was yelling at me to eat something because that was WAY too low after all that food. Again, I've been down this road before so I did not eat anything. I just kept up the hourly testing.

Two hours after having cake  I was 9.2

Alright, now I've digested enough for my blood sugar to start climbing. The next step is to see how quickly and how high I was going to climb before taking any insulin to bring it down. Because the last thing I want to do is overcompensate with the insulin and be forced to eat more food.

And hour later - I was 10.1.

It didn't look like I was climbing too quickly so I took enough insulin to (hopefully) bring my 10.1 back into the happy 5-6 range and went to bed.

I woke up two hours later and tested - I was 14.1.


Another insulin bolus to bring the 14.1 down.

Two hours later I tested again. I was 9.8. Still too high. More insulin.

Woke up at 8am and I was a very happy 4.7. I was also a very tired little diabetic from all the testing but such is life.

Small meals = as predictable as it gets with diabetes.

Big meals = crazy...but sometimes worth it anyway.

And yes, I know I can do that square bolus thing with my pump but meals like that happen so rarely that I haven't mastered that trick yet. So until I start making big, carb heavy meals a regular part of my diet, I think I'll rely on frequent testing and lots of little boluses to bring me back down safely.

1 comment:

  1. I wish everyone had CGMS. I've learned so much from it about when the carbs from my meals hit my blood. Everyone deserves to see this for themselves, too.

    (This really should be a full post on my own site, but somehow I haven't found the time to put it together yet....)

    In the last year with CGM I've seen that while some meals at some times of the day might look like bell curves, they don't need to. I've seen that most of my breakfasts are "curvy," but lunch and dinner aren't. I've found that I can make my typical breakfasts' curves much flatter by bolusing 15-20 minutes before eating. I can see that I've messed up lunch or dinner just a little bit if the CGM trace stays flat and then starts to climb after two hours; and I can see when I really got it wrong if it starts to climb sky high right after I start eating.

    As for dual/square boluses--which I did before getting CGMS--I've found that this works pretty well in many situations. (I think I based it on something I read online.) If a meal is very "complicated," I usually break the bolus into a 60-66% normal/immediate bolus and give the remainder in a square bolus over 1.5 - 2 hours. Naturally, this only works as well as my ability to guess what's in the complicated food, but it works well enough that it's what I use for most of my pizza/Indian/Chinese/Thai/Mexican meals.

    Don't fear the bolus.