Patients who successfully lost 5 kg in the first 16 weeks of the programme went on to attend for an average of 11.9 months, and greater weight loss was maintained at three years (−8.03 kg; 95% CI −9.44 to −6.62) when compared to non-completers (−3.26 kg; −4.01 to −2.51; P <0.001) and those not referred to the service (−1.00 kg; −1.15 to −0.85; P <0.001). Successful completers also had a clinically significant reduction in HbA1c (−3.7 mmol/mol; 95% CI −5.82 to −1.51) after 3 years; P ≤0.001) compared with non-completers and unsuccessful completers.