Effect of water intake on blood glucose levels
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Water Intake and Blood Glucose Levels: Key Findings
Water Intake and Postprandial Blood Glucose in Healthy Individuals
Research shows that drinking additional water after a meal can lower blood glucose levels two hours after eating in healthy people. In one study, healthy subjects who consumed extra water after both liquid and solid meals had significantly lower blood glucose at 120 minutes compared to those who did not increase their water intake. This suggests that increasing water intake after meals may help improve short-term glycemic response in healthy individuals .
Water Consumption and Blood Glucose in People with Diabetes
Several studies have examined the effects of water intake on blood glucose in people with diabetes. Regular water consumption has been shown to help reduce blood glucose levels in individuals with diabetes, supporting its use alongside insulin therapy for better glycemic control 27. In a randomized controlled trial, drinking water before meals for eight weeks led to significant reductions in fasting blood sugar, body weight, and waist circumference in patients with type 2 diabetes . Another study found that daily water intake as part of a hydrotherapy routine significantly lowered blood glucose levels in type 2 diabetes patients .
However, not all studies found immediate effects. For example, a study in diabetic patients showed that drinking 500 ml of water did not significantly change blood sugar levels within 20 minutes, though it did lower hematocrit values, indicating improved hydration .
Hydration Status and Glucose Regulation
Low water intake and poor hydration are linked to worse glucose regulation. In people with type 2 diabetes, three days of low water intake led to higher blood glucose levels during an oral glucose tolerance test, likely due to hormonal changes such as increased cortisol . Similarly, in healthy individuals who usually drink little water, increasing water intake for a short period mildly reduced daily plasma glucose concentrations and decreased cortisol levels . Another study found that higher hydration status, as measured by blood markers, was associated with better glucose tolerance in non-diabetic adults .
Hormonal Mechanisms: Vasopressin and Copeptin
Some studies suggest that the hormone vasopressin (measured by copeptin) may play a role in how water intake affects blood glucose. Increased water intake can lower copeptin levels, especially in people who usually drink little water. In these individuals, water intake also reduced fasting glucagon, a hormone that raises blood sugar, though glucose and insulin levels were not significantly affected in the short term . Pre-meal water intake in people with type 2 diabetes also reduced copeptin levels, which may contribute to improved glycemic control .
Water Intake and Fasting Blood Glucose
Drinking water before blood tests or meals can lead to a small decrease in fasting blood glucose levels. In one study, fasting blood glucose was about 4% lower in people who drank water compared to those who did not, though other factors like physical activity and nutrition also played a role .
Conclusion
Overall, increasing water intake—especially before or after meals—can help lower blood glucose levels and improve glycemic control in both healthy individuals and those with diabetes. The benefits are more pronounced in people who are usually low water drinkers or have poor hydration. Water intake may influence blood glucose through hormonal changes, such as reductions in vasopressin and cortisol. Encouraging adequate water consumption is a simple, non-pharmacological strategy that can support better blood sugar management.
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