I didn’t read it, but my first thought was they trained it to associate speech patterns with wealth and/or education, which correlates with diabetes for all the usually reasons in the US health non-care system.

Edit: I’m probably wrong:

The scientists analysed more than 18,000 recordings and 14 acoustic features for differences between those who had diabetes and those who did not.

They looked at a number of vocal features, like changes in pitch and intensity that cannot be perceived by the human ear.