Introduction 1 2 3 4 5 6 7 8 9 10 Thiamine 11 12 In this study, we sought to establish whether there is a disturbance of thiamine homeostasis prevalent in type 1 and type 2 diabetic patients in the UK and if this is linked to incipient nephropathy and markers of vascular dysfunction and early stage renal dysfunction. Methods Patients and normal healthy volunteers 1c 2 Hydrastis canadensis Assay of thiamine and phosphorylated metabolites 13 ɛ 233 ɛ 247 ɛ 247 −1 −1 14 15 Thiamine Thiamine Other biochemical measurements 16 17 18 1c Statistical analysis t U Results Patient characteristics 1 1c 1c Table 1  Characteristics of normal control volunteers and diabetic patients recruited for this study Participant type n Sex M/F Age (years) Duration of diabetes (years) 2 GFR (ml/min) Fasting plasma glucose (mmol/l) 1c Systolic BP (mmHg) Diastolic BP (mmHg) ACE inhibitor/ARB therapy Control volunteers 20 10/10 53 ± 10 – 27 ± 4 89 ± 18 5.6 ± 0.8 5.0 ± 0.2 ND ND – Type 1 diabetes 26 10/16 48 ± 15 22.1 ± 13.3 28 ± 5 93 ± 28 9.2 ± 1.7* 8.7 ± 1.2* 131 ± 21 73 ± 11 9 Type 2 diabetes 48 29/19 62 ± 12 13.0 ± 8.9** 31 ± 6 92 ± 30 9.1 ± 2.2* 8.6 ± 1.8* 141 ± 22 77 ± 9 33 Data are mean±SD. ND *p p U Thiamine status of patients with type 1 and type 2 diabetes p t 1 p p U p p Thiamine Thiamine p U Thiamine Thiamine Thiamine p U Thiamine Thiamine r p Thiamine r p 1 Fig. 1 a b Plasma Thiamine −0.274 p c Thiamine Plasma Thiamine −0.448 p  12 r p Masking of the clinical thiamine deficiency in erythrocytes by increased levels of thiamine transporter proteins 2 2 n n p p n p p U Fig. 2 a b Lanes 1–3 lanes 4–6 lanes 7–9 T  Low plasma thiamine concentration and markers of metabolic control and vascular dysfunction r p 3 r p 3 Fig. 3 a b Solid horizontal line broken horizontal line  Discussion Thiamine Thiamine Thiamine Thiamine 19 20 Thiamine Thiamine 10 Thiamine 2+ 21 22 24 O 25 26 27 28 29 30 31 32 Thiamine Thiamine 12 21 33 21 33 26 26 34 35 35 36 37 38 39 41 39 42 43 This study indicates that type 1 and type 2 diabetic patients in the UK exhibit low plasma thiamine concentration. The conventional indicator of thiamine sufficiency, erythrocyte TK activity, is masked in clinical diabetes by increased protein levels of thiamine and TMP transporters, THTR-1 and RFC-1. The deficiency of thiamine in clinical diabetes may increase the fragility of vascular cells to the adverse effects of hyperglycaemia and thereby increase the risk of developing microvascular complications. Correction of the low plasma thiamine concentration with thiamine supplements may decrease the risk of microvascular complications in diabetes. Thiamine