Aims/hypothesis: The Sydney Diabetes Prevention Program (SDPP) was a community-based type 2 diabetes prevention translational research study with screening and recruitment in the primary health care setting. We aimed to investigate the program's effectiveness in reducing risk factors for diabetes as well as the program's reach, adoption and implementation. Methods: 1238 participants aged 50-65 years at high-risk of developing type 2 diabetes were recruited by primary care physicians in the greater Sydney region. The intervention, delivered by trained allied health professionals, included an initial consultation, three group sessions/individual sessions, three follow-up phone calls, and a final review at 12 months. Biomarkers and behavioural goals were compared between baseline and 12 months. Results: At baseline, the mean age of those who entered the program was 58.8 ± 4.4 years, 63% female, and the mean body mass index was 31.6 ± 5.2 kg/m2. There was a significant weight reduction of 2 ± 4.3 kg (p < 0.02) in the 850 participants who completed the 12-month follow-up accompanied by improvements in diet (total fat, saturated fat, and fibre intake) and physical activity. There were also significant reductions in waist circumference 2.6 ± 4.7 cm (p < 0.001) and total cholesterol -0.2 ± 0.8 mmol/L (p < 0.001) but not blood glucose. The diabetes risk reduction was estimated to be 30%, consistent with similar trials. Conclusions/interpretation: This study demonstrates that a community-based lifestyle modification program is effective in reducing important risk factors for diabetes in individuals at high-risk of developing type 2 diabetes.