That was one of the earliest GI measurement studies, though the term GI was invented later. The problem with GI-based (or GL which takes quantity into account)

That was one of the earliest GI measurement studies, though the term GI was invented later. The problem with GI-based (or GL which takes quantity into account) is that insulin levels at 2 hours isn’t a good proxy for health. One really needs to measure the integral of the insulin level over 24 hours or more (which would involve lots of starving subjects). The best proxy we have for the overall insulin response over time is just net carbs.