[1] Walsall Manor Hosp, Dept Blood Sci, Walsall, W Midlands, England
[2] Univ Hosp North Midlands, Dept Clin Biochem, Stoke On Trent, Staffs, England
[3] Keele Univ, Inst Appl Clin Sci, Keele, Staffs, England
[4] Salford Royal Hosp, Dept Diabet & Endocrinol, Salford, Lancs, England
[5] Univ Manchester, Sch Med, Manchester, Lancs, England
[6] Univ Manchester, Manchester Acad Hlth Sci Ctr, Manchester, Lancs, England