This is slighlty outdated and didn't properly show the selective bias (obese people more likely to drink diet sodas to "slim down"). As they say themselves "these observational data cannot establish causality"
This more recent study
http://www.bmj.com/content/351/bmj.h3576.full shows similar findings but looked more into whether the drinks were the cause
"Although artificially sweetened beverages and fruit juice also showed positive associations with incidence of type 2 diabetes, the findings were likely to involve bias."
"Our analysis indicated possible publication bias for the associations between artificially sweetened beverages and type 2 diabetes. "
Buit they all agree its not terribly healthy to drink any of them (including fruit juices)