Carbs become glucose, and if those carbs are refined they give you a glucose spike, your body needs to generate then the right amount of insulin to neutralize that sugar, insulin transforms the sugar into fat, a type of fat that is hard to eliminate. If your body underestimates the amount of insulin that excess of glucose will cause your circulatory system and other tissues to swallow, if it overestimates it, it will generate too much insulin that will remove too much glucose from your blood and you will feel tired and hungry.

I'm pretty sure diet filled with legumes, leafy greens, has the same result.

There is no blood sugar spike when you eat 1500kcal of beans. It's slow releasing carb filled with fiber.

I'm pretty sure at /r/plantbaseddiet or /r/vegan many people state that their blood sugar or cholesterol improves.

Right yes, I didn’t mean for the high-fat variant. Just in general, low-carb, in any combo, seems to be a healthy option.

I eat about 60-70% of calories in carbs. Would that be high carb? Most of my carbs come from legumes, I get no sugar spikes, am T1 diabetic and need insulin mostly to replenish it every morning, not after every meal.

We have long vilified the wrong white crystal substance for increases in blood pressure.

Good reading on the matter is The Salt Fix.