Objectives To investigate the association between increase in physical activity and changes in cardiometabolic risk factors during a lifestyle intervention programme in routine clinical settings. Design Prospective follow-up. Setting 400 primary healthcare centres and occupational healthcare outpatient clinics in Finland. Participants Individuals at high risk for type 2 diabetes identified in the implementation project of the national diabetes prevention programme (FIN-D2D) and participating in baseline and 1-year follow-up visits. Final study group comprised the 1871 non-diabetic participants who responded at follow-up visit to a question on stability versus increase of physical activity. Interventions Lifestyle intervention. Primary outcome measures Cardiometabolic risk factors (body composition, blood pressure and those measured from fasting venous blood samples) measured at baseline and follow-up visits. Results Of the participants, 310 (16.6% of all responders) reported at follow-up having clearly increased their physical activity during the past year, while 1380 (73.8%) had been unable to increase their physical activity. Those who increased their activity decreased their weight by 3.6 kg (95% CI 2.9 to 4.3, age and sex adjusted, p<0.001) and waist circumference by 3.6 cm (95% CI 2.9 to 4.3, p<0.001) more than those who did not increase their activity. Similarly, those who increased their physical activity had greater reductions in total cholesterol (group difference in reduction 0.17 mmol/l, 95% CI 0.06 to 0.28, p=0.002), low-density lipoprotein cholesterol (0.16 mmol/l, 95% CI 0.06 to 0.26, p=0.001), low-density lipoprotein/high-density lipoprotein ratio (0.17, 95% CI 0.08 to 0.25, p<0.001) as well as fasting glucose (0.09 mmol/l, 95% CI 0.03 to 0.15, p=0.004) and 2 h glucose levels (0.36 mmol/l, 95% CI 0.17 to 0.55, p=0.023) than those who did not increase their physical activity. Conclusion Increasing physical activity seems to be an important feature of cardiometabolic risk reduction among individuals at high risk for type 2 diabetes participating in preventive interventions in routine clinical settings.