system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is a carb a carb? How do different carbs effect blood sugar levels, insulin, glycogen and diabetes?

I read that a carb is a carb and if it fits your macros then don’t worry. But then I also read that sugar is terrible for you and you should eat complex carbs because of blood sugar levels. Whats this all about? Blood sugar, glucose, insulin, and diabetes? Can someone ELI5?
gpt
As far as calories go its the same thing as far as your body is concerned. The difference is in how fast they are put into your bloodstream.

100g carbs in a bowl of oatmeal is going to be released into your bloodstream over a few hrs. Giving you a constant blood sugar level.

100g carbs in a soda will hit you bloodstream almost instantly, spiking your blood sugar, which will cause your body to produce a lot of insulin to deal with it. 

The difference is how long it takes your body to get the carbs out of the food.

As well, if the goal is to eat less calories, drinking a soda will add calories without actually making you feel like you've eaten. As well it can make you crave more carbs when your blood sugar drops back down.

So carbs and calories that make you feel full and are released slowly are better in that sense.

So yes, if it fits your macros it's fine as far as calories are concerned, but if you get 1/3 of you calories from sugar in a day you'll probably be left feeling hungry and grumpy and craving food from having low blood sugar at some points throughout the day.