Hypertonic saline infusion affects glycemic responses following glucose load in healthy men

Abstract

Low water intake and plasma hypertonicity have been independently associated with hyperglycemia and incidence of diabetes mellitus in epidemiological studies. Recent data also suggest that reducing water intake deteriorates glucose regulation in patients with type 2 diabetes. To date, it is unclear whether plasma hypertonicity would also impact glycemic control in subjects with normal glycemic and insulinemic function.OBJECTIVETo assess the effect of hypertonic saline infusion on glycemic responses to an oral glucose tolerance test (OGTT) in healthy adult men.METHODS30 healthy, non‐smoking adult men (36.6±7.0 y, 83.9±12.8 kg, body mass index 27.0±3.4 kg·m−2, HbA1c 5.2±0.3%, HOMA‐IR 1.59±0.97) were recruited for this study. Each subject underwent two experimental trials, consisting of a 2‐h intravenous infusion of saline (ISO: 0.9% NaCl and HYPER: 3.0% NaCl) at an infusion rate of 0.1 ml·kg·min−1, followed by a 4‐h oral OGTT. Blood samples were taken at 30 min intervals throughout the infusion period and during the OGTT. Plasma osmolality (POsm), glucose (Glu), angiotensin II (AngII), renin, and aldosterone (Ald) were measured and plasma volume (PV) was calculated using hematocrit and hemoglobin based on the Dill & Costill equation.RESULTSPOsm at baseline was similar between conditions (287±3 and 286±3 mmol·kg−1 in HYPER and ISO, respectively). Following the 2‐h infusion, POsm was significantly higher in the HYPER condition than the ISO condition (305‐±3 vs. 288±3 mmol·kg−1; P < 0.0001), with greater PV expansion (20.1±6.9 vs. 10.9±3.2%, P < 0.0001). In the HYPER condition, POsm remained above baseline throughout the OGTT (296±3 mmol·kg−1 at OGTT4‐h; P < 0.0001). During the OGTT, Glu in the HYPER trial was higher than in the ISO trial at 60 min (HYPER: 157±24; ISO: 145±29 mg·dL−1; P < 0.018) and 90 min (HYPER: 139±33; ISO 128±29 mg·dL−1; P < 0.038). The renin‐angiotensin‐aldosterone system was suppressed as indicated by decreased plasma values of AngII, renin, and Ald, probably due to PV expansion in both trials.CONCLUSIONPlasma hypertonicity induced by hypertonic saline infusion unfavorably affected glycemic response to an OGTT in healthy adult men.Support or Funding InformationThis research was supported by Danone ResearchThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.