Abstract Objective To determine whether exercise participation increased following a new diagnosis of diabetes using a sample of U.S. individuals aged 50 and over who did not report exercise prior to diagnosis. Methods We used data from the 2004–2010 Health and Retirement Study in a pre–post study design. Individuals newly-diagnosed with diabetes (N=635) were propensity score matched to a comparison group with no diabetes. Results In the year following a reported diagnosis, 35.7% (95% CI 32.0 to 39.5) of those newly diagnosed with diabetes initiated exercise as compared with 31.4% (95% CI 27.9 to 35.1) for the matched cohort with no diabetes, with a between-group difference of 4.3 percentage points (95% CI −0.9 to 9.4). Among individuals with fewer health risk factors at baseline, the between-group difference was 15.6 percentage points (95% CI 1.58 to 29.5). Conclusion Over 35% of persons with a new diagnosis of diabetes initiated moderate or vigorous exercise in the year following their diagnosis. Among individuals with fewer health risk factors at baseline, those newly-diagnosed with diabetes were more likely to begin exercise than those without diabetes.