I wonder how many of those are from papers discussing failure of peer review or interdisciplinary communication rather than the value of the formula itself.

Funnily enough it doesn't matter for your career. Bureaucracies stop at counting citations, sometimes weighted by impact factor.

All citations are good citations, even the bad ones.

I looked at the most cited paper between those who cite the paper in object: https://care.diabetesjournals.org/content/25/2/275.short

It states: "Mean BGwas determined using area-under-the curve analysis (10)." where (10) is the paper we are discussing about.

Hence in this paper they acknowledge the result...

Don't know about the other citers. Also It would be nice to know that, but I cannot immagine how to do it automatically

There are a lot of them that say “using the trapezoidal rule” or something and cite the paper. I think that’s a silly case of unnecessary citations (having been a coauthor on a medical paper there’s a lot of pressure to ‘grab a citation that sort of works’).

But they almost always call it “the trapezoidal rule” - the original paper is quite famous specifically because of the embarrassment it brought to medical researchers, and implication that medicine is full of doofuses who don’t know calculus is pure clickbait.

I would bet a few are also including it for the laughs....

(Tried to do this once with a tongue-in-cheek comment, but the whole section was cut for space).