Epidemiological research has shown an association between low daily total water intake and increased diagnosis of hyperglycemia, which may be due to hormones related to the hypothalamic-pituitary axis as well as the renin-angiotensin-aldosterone system (RAAS). Thus, the present study, by Johnson EC et al., hypothesized that acute low water intake would result in differential hormonal profiles and thus impaired blood glucose regulation during an oral glucose tolerance test (OGTT) in people with type 2 diabetes mellitus (T2DM). 

This study enrolled Nine men (53 ± 9 years, 30.0 ± 4.3 m∙kg−2, 32% ± 6% body fat) diagnosed with T2DM and subjected them to OGTTs in euhydrated (EUH) and hypohydrated (HYP) states in counterbalanced order. It observed that the water restriction caused hypohydration of −1.6% of body weight, with elevated plasma and urine osmolality. This condition also caused a significant main effect on serum glucose but not insulin. Furthermore, the study observed an interaction between time and condition for cortisol: a decrease from minute 0 to 120 in EUH vs. HYP. The investigated conditions showed no difference within RAAS-related hormones. Therefore, the study concluded that three days of low total water intake in people with T2DM acutely dysregulates blood glucose response during an OGTT through cortisol but not RAAS-mediated glucose regulation.

Johnson EC, Bardis CN, Jansen LT. et al., Reduced water intake deteriorates glucose regulation in patients with type 2 diabetes. Nutrition Research.2017;43: 25-32. https://doi.org/10.1016/j.nutres.2017.05.004.