They do have glucose metabolism[0], but that is the issue with CICO model already you have to start making extra rules about what is digestable and what is not.
Calories doesn't state that all. Offcourse it wouldn't because the Calories concept was made for steam engines in 1800's.[1]
Not that is matter from when it is. But maybe it's time for new ideas that do explain that conundrum of those type 1 diabetics.
The Carbohydrate-Insulin Model of Obesity[2] does have a explanation.
[0]https://www.healthline.com/health/diabetes/insulin-effects-o...
[1]https://en.wikipedia.org/wiki/Calorie
[2]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6082688/