Biochemistry measures
Recruiting centres used local results to confirm eligibility, but all biochemical tests used in analysis, except HbA1c, were centrally analysed at Exeter Clinical Laboratory. These included albumin, aspartate aminotransferase (AST), bilirubin, NT-pro-BNP, cholesterol, C-peptide, creatinine, fructosamine, glucose, HDL-cholesterol, islet autoantibodies (GAD, IA2, ZnT8), insulin, LDL-cholesterol, and triglycerides. To ensure standardisation across centres, eGFR was calculated using the CKD-EPI equation by the central database, based on serum creatinine, sex, ethnicity, and age as collected at baseline. All HbA1c assessment was performed by recruiting centre NHS laboratories to ensure results were available for screening and to inform final patient preference. HbA1c assays were CE marked, fully validated, and accredited by the UK Accreditation Service.