Minumum level of dietary carbohydrate is zero for what activity level?
There comes a point when, mathematically, gluconeogenesis simply cannot sustain anaerobic activity. Since ketones and fats cannot be burned anaerobically, at some point as you increase your daily activity level, you will require exogenous glucose to maintain your BG.
This is an interesting question, and you haven’t gotten an actual answer yet.
To directly answer your question, I believe the answer is that not all glucose that is consumed actually circulates in the blood. I believe the major reason for that is that the first stop for consumed glucose is the liver, and the liver converts a large amount of the glucose to glycogen. Muscle also stores glucose as glycogen. The degree to which glucose is stored as glycogen depends on what your glycogen stores are to start with, and how much circulating insulin you have. Insulin is needed to get the glucose into the liver and muscle cells so it can be stored.
And finally, your body is also converting excess glucose into fat for storage. It is stored as fat in fat cells, the same as fat from a meal is stored. But in addition to the glucose storage that is occurring, your body is also burning glucose at a constant rate to keep all its cells powered.
So the short answer is that the reason one gram of carb that is consumed doesn’t become one gram of circulating carb in your blood, is that your body is a dynamic machine, with all kinds of other biochemical pathways happening all the time. And a lot of these pathways prefer to use glucuse and are therefore pulling it out of the blood as soon as it is entering from the intestines. So it is similar to pouring liquid into a plastic bag that has a lot of holes in it - it is true that the faster you pour the higher the level in the bag will go, but it is also true that a lot of the liquid is leaking out as you are pouring it in so the level doesn’t rise as quickly as you might expect.
The 130 g of glucose that is recommended to keep your body powered without relying on alternate fuels takes into account these always active pathways. So the recommendation to consume 130g carb is the approximate total amount of carb that your body will burn in a day - whether from glucose or glucose that has been stored as glycogen or fat. (As the low-carbers like to point out this doesn’t REQUIRE you to eat this much carb - since you body can convert the protein and fat you eat into carb and ketones to supply the fuel needs in an alternate way).
Similarly the table that was published showing about 4 Mg/dl of rise for 1 gram of carb consumed isn’t a theoretical amount, but an experimental result which will vary somewhat from person to person and will also change depending on your metabolism at the time. So clearly, a gram of carb will not raise your BG as much if you eat it while you are exercising - because the rate of conversion from glucose to glycogen is higher since you are burning glycogen at a faster rate (i.e. the holes in the plastic bag are bigger).
If you want to learn more about some of these details I recommend the book “Type 1 Diabetes” by Ragnar Hanas. It is a great resource and is surprisingly readable, but it also has 1000 references to scientific research papers to back up the writing in the book.
One gram of glucose raises me consistently 10 pts. I know this from correcting lows. Dextrose works more quickly, but I hate the taste of dextrose tablets.
Gerri, dextrose and glucose are two names for the same thing.
I think she was referring specifically to the tablets that are made for treating lows, not pure dextrose. They have food coloring and flavors, etc and taste kinda bletchy, which is why I carry then around. Less tempting between lows.
Yes, that’s what I meant. Thanks, Jean. They taste horrible & are expensive & bulky to carry. I use jelly beans. Highly portable & cheap.
I understand the part about glucose and fructose, but what about lactose? Is it converted to glucose by the body? I imagine it must be, because lactose is where nursing babies get their energy from, but I’m just curious how it works.
Lactose is broken down by the body into glucose & raises BG. It’s made up of glucose & galactose. So, I’m not sure if you’d say that it’s converted into glucose because it already contains it.