Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Health, Sport and Exercise Science (PhD)

Degree Level



Health, Human Performance and Recreation


Stavros A. Kavouras

Committee Member

Matthew S. Ganio

Second Committee Member

Brendon P. McDermott

Third Committee Member

Sean W. Mulvenon


Copeptin, Diabetes mellitus type 2, Glucose Regulation, Hydration, Osmolality, Type 2 Diabetes, Vasopressin


Previous evidence suggests the hormone arginine vasopressin (AVP) may be a modifiable factor contributing to hyperglycemia. Significant differences in urine concentration and copeptin, a marker for AVP, have been observed between low and high water drinkers. Purpose: The purpose was to investigate the acute effect of adequate water intake on glucose regulation in low drinkers. Methods: 7 healthy (5 males, 2 female) low drinkers were recruited using a water frequency questionnaire (WFQ), spot and 24-h urine sample (age 43±6 y, BMI 30.9±3, WFQ volume 823±403 mL∙d-1, 24 h Uosm 961±105 mmol∙kg-1, copeptin 8.17±3.05 pmol∙L-1). During two experimental protocols, participants remained in the laboratory for 11 h and were provided either the Institute of Medicine’s (IOM) recommended amount of water excluding food (males: 3 L, females: 2 L) or an amount representing the bottom quartile of water consumption observed in the National Health and Nutrition Examination Survey (NHANES) (males: 0.5 L, females: 0.4 L). Food was provided to participants and standardized to body weight (100 kJ∙Kg-1) using a consistent ratio of macronutrients. Results: 11 h urine volume was significantly higher in the high water trial (P < 0.001). 11 h UOsm was significantly higher in the low water trial (P < 0.001). Plasma osmolality was acutely lower as a result of increased water intake (P = 0.007). Copeptin was suppressed as a result of high water intake (P = 0.019). Glucagon was similar between trials (P = 0.372), however, there was a main effect of water intake on cortisol (P = 0.009). No differences in plasma glucose were found due to water intake (P = 0.07). Conclusion: Acute increases in water intake do not reduce post-prandial plasma glucose responses in low drinkers, however, cortisol may be acutely reduced.