Seeking clearer explanation for source of glucose which basal rates should cover

Jaedima · #1 10-21-2012, 11:04 AM

We've gotten plenty of emphasis on the importance of basal rate testing, but I'd like a clearer explanation of exactly what the basal insulin is supposed to cover.

Is it for circulating glucose in the blood? Glycogen stores that get released from the muscle tissue or liver? Slower-digesting glucose that enters the bloodstream on the tail end (i.e., >3hrs) after a meal?

Basically, if the basal rate is too low at a given time period and we see the BG rise, where is that glucose coming from?

nanhsot · #2 10-21-2012, 11:51 AM

Quote:

Originally Posted by Jaedima

We've gotten plenty of emphasis on the importance of basal rate testing, but I'd like a clearer explanation of exactly what the basal insulin is supposed to cover.

Is it for circulating glucose in the blood? Glycogen stores that get released from the muscle tissue or liver? Slower-digesting glucose that enters the bloodstream on the tail end (i.e., >3hrs) after a meal?

Basically, if the basal rate is too low at a given time period and we see the BG rise, where is that glucose coming from?

I think it's a complicated process but the simple explanation is that the liver continually releases stored glucose into the bloodstream so the body can function properly. The basal is counteracting that.

That's my understanding anyway.

Lee · #3 10-22-2012, 07:12 AM

Everybody's bodies need insulin and glucose to survive. The muscles and organs need it to live. Since your child's body no longer makes insulin, the basal insulin covers what is needed to run, day in and day out, 24-7 without food.

Essentially, at least in theory, the basal should be set to a dosage that keeps the body at optimum levels without needing food to bring up blood sugar or corrective insulin to lower it. But yeah, that never really happens.

http://type1diabetes.about.com/od/in...us-Insulin.htm

C6H12O6 · #4 10-22-2012, 08:31 AM

The above two answers are exactly correct. This is from my nutrition textbook

?Regulating Blood Glucose
Normally, fasting blood glucose, or more precisely, plasma glucose, measured after an 8- to 12-hour overnight fast, is maintained at about 3.3 to 5.5 mmol/L. (60 - 99) Maintaining this level ensures adequate glucose will be available to body cells. A steady supply of glucose is particularly
important for nerve cells, including those in the brain and red blood cells, because these cells rely almost exclusively on glucose as an energy source.?

As you know insulin is the hormone that allows the glucose to enter the cells in order to nourish them . Your brain needs this glucose. This is why you get all of the cognitive symptoms when BG is low

denise3099 · #5 10-22-2012, 12:30 PM

Agree with above responses.
Think of it this way--insulin does not remove glucose from blood, but rather lets glucose from the blood into the cells. Your cells need to eat all the time so what you eat goes to them , the rest is stored to deliver over time. If your blood glucose is low, not enough will be there to feed your brain. If it's high it will tear through capillaries and organs. Insulin all day means cells get some glucose all day.

swellman · #6 10-22-2012, 01:07 PM

Think of insulin as the key to open the door to allow the glucose into cells to give them fuel - exactly what was posted here previously.

This is why, when the body or cells do not have enough glucose as fuel, fats and fatty acids are used alternatively as fuel which produce ketones.

Jaedima · #7 10-22-2012, 01:44 PM

Thanks for all the replies! It sounds like the immediate answer to my question is "liver glycogen." I just read that glucose from muscle glycogen doesn't pass into the bloodstream, so it all must be coming from the liver's glycogen stores.

What I'm wondering now is, (1) what's the typical circadian fluctuation in liver glycogen output, and (2) what are the factors that influence it?

(While writing this I just found a summary of Hormones that influence blood glucose level which seems to address #2. But it would still help me to have an overview of their typical combined effect during the course of the day and night.)

In doing basal rate testing for my son one morning, I found that after a zero-carb breakfast at 9am, his BG stayed pretty stable through ~1:30pm or so, then dropped by 2pm or 2:30pm, even though the basal rate stayed the same. But he didn't have lunch until after 2pm. If he'd eaten a zero-carb lunch around 1pm, would his BG perhaps have stayed the same? (Because the non-carb food supplied alternate energy sources, thereby preventing his body from needing to dip into the circulating plasma glucose as much?) I also found out that the body can synthesize some glucose from amino acids. Could a protein source at an earlier lunch have prevented the BG dip? (That is, I'm questioning whether it's accurate to conclude that the 1pm-3pm basal rate should be reduced, or if it's not a good test since he should have eaten earlier.)

On the flip side, we've found that despite having fairly stable BG levels for a while (including at night), recently we've noticed our son's BG going up at night, more than 3-4 hours after dinner, even though BG levels had been within range and pretty stable. I know we need to repeat our basal rate tests at night to figure this out, but I'd like to understand what could be causing this so I can better anticipate what to do in the future. Does this mean that the meal was digested slowly, so more carbs were still entering the system even after 3-4 hours post-dinner? Is this just a consequence of reduced physical activity during the day? Could this signal that he's entering some kind of growth spurt (with increased growth hormone release at night)?

Lee · #8 10-22-2012, 02:06 PM

What you are seeing doesn't have to do with food - it has to do with his bodies natural fluctuations.

denise3099 · #9 10-23-2012, 10:20 AM

I don't have good answers to your questions but I encourage you to think of insulin needs as extremely fluid. Basal needs could be different based soley on activity. He might have gone lower in the afternoon b/c he was watching tv all morning and jumping on the bed in the afternoon or playing outside or any non-sedentary activity or even doing a hard puzzle. My daughter would go low playing the violin, esp when she was learning a new piece--mental energy requires lots of sugar.

My point is that you won't get it exact. Yes, look for patterns and do basal testing, but it's important to look at the big picture.

nanhsot · #10 10-23-2012, 11:38 AM

Quote:

Originally Posted by Jaedima

Thanks for all the replies! It sounds like the immediate answer to my question is "liver glycogen." I just read that glucose from muscle glycogen doesn't pass into the bloodstream, so it all must be coming from the liver's glycogen stores.

What I'm wondering now is, (1) what's the typical circadian fluctuation in liver glycogen output, and (2) what are the factors that influence it?

(While writing this I just found a summary of Hormones that influence blood glucose level which seems to address #2. But it would still help me to have an overview of their typical combined effect during the course of the day and night.)

In doing basal rate testing for my son one morning, I found that after a zero-carb breakfast at 9am, his BG stayed pretty stable through ~1:30pm or so, then dropped by 2pm or 2:30pm, even though the basal rate stayed the same. But he didn't have lunch until after 2pm. If he'd eaten a zero-carb lunch around 1pm, would his BG perhaps have stayed the same? (Because the non-carb food supplied alternate energy sources, thereby preventing his body from needing to dip into the circulating plasma glucose as much?) I also found out that the body can synthesize some glucose from amino acids. Could a protein source at an earlier lunch have prevented the BG dip? (That is, I'm questioning whether it's accurate to conclude that the 1pm-3pm basal rate should be reduced, or if it's not a good test since he should have eaten earlier.)

On the flip side, we've found that despite having fairly stable BG levels for a while (including at night), recently we've noticed our son's BG going up at night, more than 3-4 hours after dinner, even though BG levels had been within range and pretty stable. I know we need to repeat our basal rate tests at night to figure this out, but I'd like to understand what could be causing this so I can better anticipate what to do in the future. Does this mean that the meal was digested slowly, so more carbs were still entering the system even after 3-4 hours post-dinner? Is this just a consequence of reduced physical activity during the day? Could this signal that he's entering some kind of growth spurt (with increased growth hormone release at night)?

I appreciate your need for science in diabetes, I share your need. But if I have learned nothing else about this disease it's that it doesn't follow the rules! It could be any of the above (slow digestion, decreased activity, hormones) or it could be something entirely different like illness or anxiety.

While there are certain things that can be extrapolated from person to person, there is a reason we use the term YDMV (your diabetes may vary) so frequently; every person seems to react differently. Yes, we can predict and make generalizations but at the bottom is the fact that factors outside our knowledge and individual variations happen.

I will say that my son has a VERY strong dawn phenomenon and his basal needs are doubled during the night as compared to daytime, so cortisol may be a factor in what you are seeing as well.

Just as soon as we make a basal change it seems like it changes again, so realize it's an ongoing, everchanging thing. My son was low all last week, just as we decided to lower his basal, this week he's been going high (BEFORE we made the change). It's maddening!