Can drinking lots of water lower blood sugar?

December 17, 2025 •

5 min read

A person consuming more than 33.8 fluid ounces of water a day has a 28% lower risk of developing hyperglycemia, according to some studies. While water isn't a replacement for insulin or other diabetes medications, staying properly hydrated is a crucial and often overlooked part of blood sugar management.

Quick Summary

Drinking water aids blood sugar control indirectly by helping the kidneys flush excess glucose and preventing blood concentration from dehydration. Adequate hydration supports overall metabolic function, insulin sensitivity, and weight management, which collectively assist in regulating blood sugar levels.

Key Points

Indirect Effect: Drinking water helps manage blood sugar indirectly, primarily by helping the kidneys flush excess glucose and preventing blood concentration.
Dehydration Raises Blood Sugar: Lack of sufficient fluid concentrates blood glucose and triggers stress hormones, causing blood sugar levels to rise.
Kidney Function Support: Adequate hydration allows the kidneys to work efficiently in filtering and excreting extra glucose through urine.
Weight Management Aid: Drinking water can suppress appetite and replace high-sugar beverages, which assists in weight control and improves insulin sensitivity.
Improves CGM Accuracy: Staying hydrated is crucial for maintaining the consistency of interstitial fluid, leading to more reliable readings from Continuous Glucose Monitors.
No Replacement for Medication: Water is a supportive tool for blood sugar management, not a substitute for prescribed medication, insulin, or other medical treatment.

Understanding the Link Between Hydration and Blood Sugar

For individuals with diabetes or prediabetes, maintaining stable blood glucose levels is paramount. The relationship between hydration and blood sugar is not as simple as water directly 'washing away' sugar, but it is deeply interconnected through several bodily processes. Proper hydration prevents dehydration, which can worsen blood sugar control, while also optimizing the body's natural sugar-regulating mechanisms.

The Indirect Mechanisms: How Water Affects Glucose

Drinking water influences blood sugar levels primarily through indirect, supportive functions. These mechanisms explain why consistent hydration is a key pillar of good metabolic health.

Diluting Blood Glucose Concentration: When you become dehydrated, the amount of water in your bloodstream decreases, causing the glucose to become more concentrated. This makes your blood sugar reading appear higher. Drinking water helps restore the proper fluid balance, effectively diluting the glucose concentration back to its true level.
Supporting Kidney Function: The kidneys play a critical role in filtering waste from your blood, including excess glucose. When blood sugar is high, the kidneys work overtime to excrete the extra sugar through urine. Drinking plenty of water supports the kidneys, enabling them to work more efficiently to flush out this excess glucose.
Reducing Vasopressin Levels: The hormone vasopressin can stimulate the liver to produce sugar. Studies suggest that increased water intake can help lower vasopressin levels, which, in turn, can contribute to improved glycemic control.

The Dehydration and High Blood Sugar Cycle

For people with diabetes, dehydration and hyperglycemia can create a vicious cycle that is important to recognize and break.

High blood sugar leads to increased urination: The body's attempt to remove excess glucose from the bloodstream results in frequent trips to the bathroom.
Increased urination leads to fluid loss: This fluid loss can rapidly cause dehydration.
Dehydration concentrates blood sugar: With less water in the blood, the glucose concentration rises further, worsening hyperglycemia.
Cortisol spikes blood sugar: Dehydration can also trigger the release of stress hormones like cortisol, which further increases blood sugar levels.

This cycle can escalate if left unaddressed, leading to serious complications like diabetic ketoacidosis (DKA) in extreme cases.

Beyond the Quick Fix: Long-Term Hydration Benefits

While a single glass of water won't instantly fix a blood sugar spike, consistent, long-term hydration offers substantial metabolic benefits.

Prevents Chronic Dehydration: Regular water intake prevents the chronic, low-level dehydration that can contribute to insulin resistance over time.
Supports Weight Management: Often, thirst signals are mistaken for hunger. Drinking water can increase satiety and help regulate appetite, which is crucial for maintaining a healthy weight—a primary factor in managing type 2 diabetes. Replacing sugary beverages with water is a simple yet powerful change.
Enhances Insulin Sensitivity: Research suggests that adequate hydration can improve insulin sensitivity, allowing the body's cells to use insulin more effectively.

Water vs. Sugary Drinks: A Clear Comparison

When managing blood sugar, the choice of beverage is critical. A comparison between water and sugar-sweetened drinks highlights why water is always the preferred option.


Aspect	Plain Water	Sugary Drinks (Soda, Juice)
Effect on Blood Sugar	Does not raise blood sugar; helps manage existing levels	Causes rapid spikes in blood sugar due to high sugar content
Caloric Impact	Zero calories, beneficial for weight management	High in empty calories, contributes to weight gain and insulin resistance
Hydration Quality	Optimal for rehydration	Sugary content can contribute to dehydration
Nutritional Value	Supports bodily functions, has no negative additives	Lacks nutritional benefits, high in added sugars
Kidney Health	Supports efficient kidney function	Strains kidneys, especially with high sugar load

Hydration and CGM Readings

For those who use Continuous Glucose Monitors (CGMs), proper hydration is also important for accuracy. CGMs measure glucose in the interstitial fluid, the fluid between your cells. Dehydration can cause this fluid to become more concentrated, leading to inaccurate CGM readings. Staying hydrated ensures the interstitial fluid remains consistent, providing more reliable data for effective diabetes management.

Putting Hydration into Practice

Aim for a Target: While individual needs vary, a common starting point is to aim for around 8-10 glasses (approx. 2-2.5 liters) of water per day. Adjust this based on your activity level, climate, and overall health.
Flavor Your Water: If plain water is unappealing, infuse it with slices of lemon, cucumber, mint, or berries for a flavorful, sugar-free alternative. Unsweetened herbal teas are another excellent option.
Use Hydration Reminders: Set alarms or use a phone app to remind you to drink water throughout the day, especially if your thirst signals are diminished.
Eat Water-Rich Foods: Foods with high water content, such as watermelon, cucumbers, and strawberries, also contribute to your daily fluid intake.
Hydrate Before and During Exercise: Physical activity is a powerful tool for lowering blood sugar, but it increases fluid loss. Be sure to hydrate well before, during, and after your workout.

Conclusion

Drinking lots of water does not directly reduce blood sugar in the same way as medication, but it is an essential and effective supportive strategy. Proper hydration prevents the blood sugar concentration that occurs during dehydration, helps the kidneys flush out excess glucose, and contributes to better metabolic health overall. Consistent hydration, especially when combined with a balanced diet and regular exercise, is a vital and proactive measure for anyone seeking to better manage their blood sugar levels and minimize the risk of diabetes complications. Always consult your healthcare provider to create a comprehensive diabetes management plan tailored to your specific needs.

Other Lifestyle Factors for Blood Sugar Control

While hydration is important, it is only one piece of a complete blood sugar management strategy. Combining it with other healthy habits yields the best results:

Regular Exercise: Physical activity increases insulin sensitivity, allowing your muscles to use glucose for energy more efficiently. Aim for a mix of aerobic and strength training.
Balanced Diet: Focus on complex carbohydrates, lean protein, healthy fats, and fiber to slow down glucose absorption. Limiting refined carbs and added sugars is key.
Stress Management: Stress hormones like cortisol can raise blood sugar levels. Practicing relaxation techniques such as mindfulness or yoga can help.
Adequate Sleep: Poor sleep can increase insulin resistance. Aim for 7-9 hours of quality sleep per night.

Disclaimer

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Please consult with a healthcare professional for personalized guidance regarding your blood sugar management and hydration needs.

Frequently Asked Questions

While drinking water helps manage blood sugar levels, it is not a quick fix for lowering a high blood sugar spike. It primarily supports the body's long-term glucose regulation by helping the kidneys function properly. For rapid changes, follow your doctor's prescribed plan, which may include insulin or exercise.

General recommendations suggest aiming for about 8-10 glasses (2-2.5 liters) of water daily, but individual needs vary based on factors like activity level, climate, and body size. It is best to consult a healthcare provider for personalized guidance.

Dehydration increases blood sugar by making the glucose in your bloodstream more concentrated due to the reduced fluid volume. Additionally, dehydration triggers the release of stress hormones, like cortisol, which can also elevate glucose levels.

Yes, studies suggest that proper hydration can positively affect insulin sensitivity, helping the body's cells use insulin more effectively to absorb glucose. This is a long-term benefit of consistent hydration.

Great alternatives to plain water include unsweetened herbal teas, water infused with lemon or cucumber, and plain mineral or sparkling water. Avoid sugary beverages like soda, juice, and sweetened coffees.

Yes, hydration levels can impact the accuracy of Continuous Glucose Monitor (CGM) readings. Since CGMs measure glucose in interstitial fluid, dehydration can lead to more concentrated fluid and potentially inaccurate readings.

While staying hydrated is vital, it is possible to drink too much water, especially for individuals with certain medical conditions. This can lead to a potentially dangerous imbalance of electrolytes. Drink based on thirst and general recommendations, but avoid forcing excessive amounts.

While water doesn't directly 'flush' sugar from your blood, it supports the kidneys' function in filtering and excreting excess glucose through urine. Adequate hydration ensures this process is as efficient as possible.