The association between plasma selenium and new-onset diabetes in hypertensive adults is still unclear. We aimed to evaluate the relationship of baseline plasma selenium with new-onset diabetes and examine possible effect modifiers in a post-hoc analysis of the China Stroke Primary Prevention Trial (CSPPT).A total of 2367 hypertensive, non-diabetic patients with plasma selenium measurements at baseline were included. The primary outcome was new-onset diabetes, defined as physician-diagnosed diabetes or use of glucose-lowering drugs during the follow-up period, or fasting glucose (FG) ≥126.0 mg/dL at the exit visit.At baseline, higher FG levels were found among participants with plasma selenium in quartile 4 (≥94.8 μg/L) (β, 1.64 mg/dL; 95%CI: 0.54, 2.73) compared to those in quartiles 1-3. During a median follow-up duration of 4.5 years, new-onset diabetes occurred in 270 (11.4%) participants. Graphic plot showed a positive association between baseline selenium levels and risk of new-onset diabetes. This was further confirmed by adjusted regression analyses; the odds ratios (OR) for new-onset diabetes comparing quartile 4 (≥94.8 μg/L) to quartiles 1-3 was 1.36 (95%CI: 1.01, 1.83). No clear trend was evident across quartiles 1-3.Our data suggest that high plasma selenium (≥94.8 μg/L) was associated with increased risk of new-onset diabetes in hypertensive patients.