An analysis of data from the Coronary Artery Risk Development in Young Adults (CARDIA) study has revealed that using marijuana during young adulthood results in an increased risk of prediabetes, but not diabetes mellitus, by middle adulthood. The study included data from >3,000 individuals who did not have prediabetes or diabetes mellitus at CARDIA examination year 7. Participants were asked to self-report their marijuana use throughout the study and underwent a follow-up examination at least once over the subsequent 18 years (up to CARDIA examination year 25). At the end of the follow-up period, the participants who reported a lifetime use of marijuana of ≥100 times had an increased risk of prediabetes compared with those who reported never using marijuana.