Is it the lack of sugar or is that people who don't put sugar in their coffee have a bunch of other things they do? Maybe people who don't put sugar in their coffee are less likely to eat donuts. Maybe people who don't put sugar in their coffee are more likely to workout. Maybe people who don't put sugar in their coffee are more like to have better genes for T2D and that same collection of genes makes the predisposed to not put sugar in their coffee.
I'm not saying sugar isn't bad. It is! (I don't put sugar in my coffee) But, 1 teaspoon a cup doesn't sound like enough to have a measurable impact without knowing that everything else about the people is the same.
Reminds me this podcast
https://podcast.clearerthinking.org/episode/252/gordon-guyat...
Here’s a great video about how these researchers are using big data to reveal insights into nutrition: https://www.youtube.com/watch?v=X8JQtwLNKXg
"Smart" home devices work as expected for about a year and then they fail in new and exciting ways, and then you replace them.