INTRODUCTION: Patients with type 1 diabetes are susceptible to hypertension, possibly resulting from increased salt sensitivity and accompanied changes in body fluid composition. We examined the effect of a high-salt diet (HSD) in type 1 diabetes on hemodynamics, including blood pressure (BP) and body fluid composition. RESEARCH DESIGN AND METHODS: We studied eight male patients with type 1 diabetes and 12 matched healthy controls with normal BP, body mass index, and renal function. All subjects adhered to a low-salt diet and HSD for eight days in randomized order. On day 8 of each diet, extracellular fluid volume (ECFV) and plasma volume were calculated with the use of iohexol and 125I-albumin distribution. Hemodynamic measurements included BP, cardiac output (CO), and systemic vascular resistance. RESULTS: After HSD, patients with type 1 diabetes showed a BP increase (mean arterial pressure: 85 (5) mm Hg vs 80 (3) mm Hg; p<0.05), while BP in controls did not rise (78 (5) mm Hg vs 78 (5) mm Hg). Plasma volume increased after HSD in patients with type 1 diabetes (p<0.05) and not in controls (p=0.23). There was no significant difference in ECFV between diets, while HSD significantly increased CO, heart rate (HR) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in type 1 diabetes but not in controls. There were no significant differences in systemic vascular resistance, although there was a trend towards an HSD-induced decrease in controls (p=0.09). CONCLUSIONS: In the present study, patients with type 1 diabetes show a salt-sensitive BP rise to HSD, which is accompanied by significant increases in plasma volume, CO, HR, and NT-proBNP. Underlying mechanisms for these responses need further research in order to unravel the increased susceptibility to hypertension and cardiovascular disease in diabetes. TRIAL REGISTRATION NUMBERS: NTR4095 and NTR4788.

extracellular fluid volume, hypertension, plasma volume, salt, salt sensitivity, sodium, systemic vascular resistance, type 1 diabetes, vasodilation,
BMJ open diabetes research & care
Department of Internal Medicine

Wenstedt, E.F.E. (Eliane F E), Rorije, N.M.G. (Nienke M G), Olde Engberink, R.H.G. (Rik H G), van der Molen, K.M. (Kim M.), Chahid, Y. (Youssef), Danser, A.H.J. (A H Jan), … Vogt, L. (2020). Effect of high-salt diet on blood pressure and body fluid composition in patients with type 1 diabetes: randomized controlled intervention trial. BMJ open diabetes research & care, 8(1). doi:10.1136/bmjdrc-2019-001039