6afb5300_usation___HealthNewsReview_org__Study_design
Compared with women who reported 0 cups of coffee per day, women who consumed 6 or more had a 22% lower risk of diabetes Overall, those who drank the most [coffee] were 22 percent less likely to have diabetes, with decaf drinkers reaping somewhat greater benefit [Problem] 22 percent less likely is correct; reaping greater benefit is causal. [Suggested language] Overall, those who drank the most coffee were 22 percent less likely to have diabetes. But, this type of study cannot prove that coffee drinking actually caused the lower chance of getting diabetes. A randomized trial is needed to show cause and effect. [Study design] 
Prospective cohort study of the relationship between coffee consumption and diabetes among postmenopausal women (observational)
Observational Studies - Does The Language Fit The Evidence? - Association Versus Causation - HealthNewsReview.org
Study design