Risk Estimates for Diabetes and Hypertension with Different Physical Activity Methods, Purpose To estimate risks of incident Type 2 Diabetes (T2D) and Stage 2 and greater hypertension associated with self-reported and accelerometer-determined moderate-vigorous physical activity (MVPA) separately and adjusted for each other. Methods The sample included 2,291 black and white men and women, ages 38-50, in the CARDIA (Coronary Artery Risk Development in Young Adults) Fitness Study, conducted during the Year 20 core CARDIA exam. Accelerometer-determined (Actigraph, LLC. model 7164) MVPA (MVPA-Acc), assessed at Year 20, was defined as mins/day of counts >2020/min. Self-reported MVPA (MVPA-SR) was assessed at Year 20 using the CARDIA Physical Activity History. Incident T2D was ascertained at Years 25 and 30 from fasting glucose, 2 hr GTT, HbA1c or diabetes medication; incident hypertension was ascertained at those same times from measured blood pressure or use of antihypertensive medications. Modified Poisson regression models estimated relative risk (RR) of incident (Years 25 and 30) T2D or hypertension, associated with middle and high tertiles of Year 20 MVPA-Acc alone, Year 20 MVPA-SR alone, and both, adjusted for each other, relative to bottom tertile. Results In men, MVPA-Acc, but not MVPA-SR, was associated with a 37-67% decreased risk of incident T2D in a dose response relation that persisted with adjustment for BMI, Similar associations were observed in women, although the risk reduction was similar in the second and third tertiles, relative to the bottom tertile. In both men and women, MVPA-Acc was marginally associated with reduced risk of incident Stage 2 and greater hypertension, but only after adjustment for BMI, while MVPA-SR was not associated in either sex. Conclusions Accelerometer-determined MVPA may provide more consistent risk estimates for incident diabetes than self-reported MVPA. ADDRESS FOR CORRESPONDENCE: Barbara Sternfeld, PhD, Emeritus, Division of Research, Kaiser Permanente, 270 Purdue Ave., Kensington, CA 94708, bsternfeld@gmail.com. 510-847-6246 The Coronary Artery Risk Development in Young Adults Study (CARDIA) is conducted and supported by the National Heart, Lung, and Blood Institute (NHLBI) in collaboration with the University of Alabama at Birmingham (HHSN268201800005I & HHSN268201800007I), Northwestern University (HHSN268201800003I), University of Minnesota (HHSN268201800006I), and Kaiser Foundation Research Institute (HHSN268201800004I). Accelerometer data collection was supported by grants R01 HL078972 from the NHLBI. This manuscript has been reviewed by CARDIA for scientific content. CONFLICT OF INTEREST: The authors have no conflicts to declare. The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM. Accepted for Publication: 24 June 2019. © 2019 American College of Sports Medicine