system
Given the following post, respond as if you're commenting on Reddit:
human
If all carbs break down into glucose then why does it matter what you eat?

I know that diabetes can't handle a super quick load of glucose and would benefit from startch etc, but for a normal person, if they just need to get their calories in, and eat about 3 to 4 meals a day, then does it really matter?

What about those trying to gain weight through lifting? Why does it matter what form of carbs you are getting?
gpt
Some carbs are more easily digestable than others, ie they take longer and more initial energy to break down. Glucose for example is really quickly available since it is the substrate of glycolylsis, as you may know. Other monosaccharides like fructose are also immediately available since thy can be converted into gluccose quickly most of the time. Polysaccharides like starch (amylose and amylopectin; long glucose chains) are a little harder to digest since you need a good amount of enzymes to even break the glucose chains into smaller chainlettes until you end up with disacccharides called maltose, for which you need yet another enzyme to break down into glucose monosaccharides. The body needs a little time and energy to produce these enzymes, so that procedure takes a little longer. The amylopectin part of starch is even harder to break down because of glucose side chains, rendering about 30%-40% of starch practically undigestable (comparable to fiber).

The slower release of glucose from starch vs the immediate availability of glucose from direct consumption (or from disaccharide sources like saccharose or lactose) does not only have an effect on blood sugar, but also on satiety (or the lasting of satiety). The immediately available glucose is used up way quicker while the glucose that is getting slowly released lasts for longer. 

From a dietary and psychological perspective it is favorable to eat food products that satiate for a longer time without you developing food cravings and succombing to those in the end. From a sport perspective, you need different products depending on what you are trying to achieve: endurance athletes (eg marathon, long-distance) need fatty and starchy products since their most prevalent muscle fiber type (type 1) can and will use those high-energy, but slow release energy sources, while strength sports athletes (eg lifting) benefit from a starchy and more sugar rich diet because of their muscle fiber type (type 2b and 2x) and their dependence on immediately available glucose from the circulation and the muscles glucose deposit, glycogen (which is chemically very similar to starch). To effectively build muscle you also need a protein rich diet of course.