A negative diabetes screening test may unintentionally provide reassurance, resulting in reduced incentive to follow a healthy lifestyle. The purpose of this study is to assess negative test result effects on lifestyle and risk perception at 4 years follow-up. Risk perception and changes in smoking, physical activity, body mass index (BMI), and waist circumference were compared between 706 high-risk participants with a negative test result and 706 high-risk participants not offered screening (controls) in a randomized controlled trial of diabetes screening. Negative-screened individuals experienced a small but significant increase in BMI and waist circumference, but there was no significant difference with controls. The negative-screened group had significantly higher perception of risk of developing diabetes (p = 0.009) than controls, but no differences were observed in perceived personal control, worry, and optimistic bias. Screening negative for diabetes did not lead to overt long-term changes in lifestyle, despite a high perception of risk of developing diabetes. (ISRCTN75983009.).