Participants
TYPE 2 DIABETES
Participants were identified in primary care and from existing research cohorts in the UK. People with type 2 diabetes were eligible if aged 30-80 years on stable doses of metformin alone, or metformin and a sulfonylurea with HbA1c >58mmol/mol (>7.5%) and ≤110mmol/mol (≤12.2%). All participants gave written informed consent and were compensated for travel expenses only. Ethnicity was self-reported by participants using standard 2011 UK Office for National Statistics codes.