Date of Graduation

5-2015

Document Type

Thesis

Degree Name

Bachelor of Arts

Degree Level

Undergraduate

Department

Biological Sciences

Advisor

Kavouras, Stavros

Reader

Ganio, Matthew

Second Reader

Evans, Timothy

Third Reader

McIntosh, Matt

Abstract

Daily total water intake (TWI) has been linked to a number of chronic diseases, such as urolithiasis and chronic kidney disease. Additionally, epidemiological and animal model data have tied low TWI to impaired blood glucose regulation. However, the effect of a fluid intake intervention on blood glucose regulation has not yet been observed in humans. PURPOSE: Thus, the purpose of the current investigation is to determine if the response to an oral glucose tolerance test (OGTT) is altered by manipulation of hydration status in people with diabetes. METHODS: Nine men (53±9 y, 94.9± 23.8 kg, 1.75± 0.11 m, 30.0± 4.3 m∙kg-2, 31.5± 6.5 %BF) who had previously been diagnosed with type II diabetes mellitus (T2DM) (hemoglobin A1C; 6.8±0.9 %) were recruited to take part. Participants completed two OGTTs in a euhydrated and hypohydrated state one week apart in a counterbalanced order. Euhydration was achieved by standard water prescription in line with the dietary reference intakes for water, and hypohydration was achieved through progressive water restriction over three days leading up to the OGTT. Blood samples were taken at time points 0, 15, 30, 45, 60, 90, 120 min of the OGTT. RESULTS: The changes in TWI in the three days before each trial resulted in significantly lower body mass (-1.5±1.5 kg; p = 0.017) and increased urine specific gravity (0.017±0.009; p = 0.001), and plasma osmolality (10±8 mmol∙kg-1). Repeated measures analysis of variance identified a main effect of condition for blood glucose concentration F[1,48] = 10.772, p = 0.011, but not for insulin concentration F[1,48] = .657, p = 0.441. Insulin sensitivity calculated with the Matsuda index revealed attenuated insulin sensitivity during the hypohydrated trial (3.59±3.28) versus the euhydrated trial (4.10±3.78; t[8] = 2.834, p = 0.022) CONCLUSION: Hypohydration elicits an acute, negative effect on the blood glucose response to OGTT in men with T2DM. Although, blood insulin did not change, blood glucose and insulin sensitivity were reduced during the euhydrated trial. This suggests that inadequate TWI can negatively impact blood glucose regulation via decreased insulin sensitivity.

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