Insulin/Hypoglycemia question...

[Philly85]

Current BSN student here. I feel pretty embarrassed asking this question, but I know it's important to ask questions, no matter how "dumb" I think they might be. Maybe it's because my mind is just so overloaded with school stuff or maybe it's just the fact that I never really learned about Diabetes as in depth as I thought I had, but here goes...

So, I understand that glucose is absorbed into the blood stream via the small intestine and then the beta cells of the pancreas release insulin into the bloodstream to signal the body's cells to bring in the glucose.

In class the other day, my Pharm professor was talking about how dangerous hypoglycemia is and that sometimes it may be a result of over-treating with insulin. She was talking about how the brain would not be getting enough energy and the severe repercussions, etc.

What I'm having trouble with is...if there was too much insulin, which caused even MORE glucose to be taken up by the body's cells from the blood, then wouldn't the brain have even more glucose than it needed, b/c even more glucose is going into the brain cells? Or are we assuming that the blood containing the glucose hasn't had a chance to circulate up to the brain yet?

Is it because most insulin is given with meals to simulate the body's own natural timing, and you are then causing all of the newly formed glucose to be absorbed by cells that are closer to the point of absorption in the small intestine before it has a chance to circulate up to the brain? How fast does blood flow through the body? Wouldn't it get up to the brain pretty quickly?

If you give too much rapid-acting insulin with a meal vs say too much of an XR dose that is given throughout the day via a pump, would that be worse?

I was too embarrassed to ask in class and feel pretty sheepish asking on here...any help or video links, etc is appreciated.

Thanks in advance for being such a great community!

[NightNerd, MSN, RN]

Think about where insulin actually puts the glucose. The level that you check on the glucometer is the glucose that is actually available in the bloodstream. When insulin starts taking effect, what does it do with the excess glucose to "store" it?

[offlabel]

Philly85, this is a great, insightful question. Good job.

The answer has to do with the way the central nervous system utilizes glucose. It isn't dependent on insulin like other tissues are (muscle, adipose). There needs to be a certain amount of circulating sugar for the CNS to work and if the insulin transports too much of it into non CNS tissue, there isn't enough left over for the brain, which is when you get altered sensorium and even seizures if the sugar gets low enough. It's also why people get diaphoretic and tachycardic...the SNS branch of the autonomic nervous system starts to fire because of the hypoglycemia.