Diabetes And Hydration


Do you know why hydration is so important when we talk about diabetes?

It is because, with diabetes, the kidneys struggle with an excessive glucose level. The excess glucose is expelled through urine, and as other fluids are also excreted in this process, it causes dehydration.1 Feeling thirsty is one of the main symptoms of diabetes. It is also a determinant of the negative implications of diabetes and something that needs to be monitored. 

The first step for people living with diabetes is always to check their blood sugar levels and keep track of it. According to the National Institute for Clinical Excellence (NICE), the recommended blood sugar range for non-diabetic people before a meal is between 4.0 and 5.9 mmol/L and between 4 and 7 mmol/L for people with type 1 and 2 diabetes.2

There are three types of diabetes:

  • Type 1 diabetes is a condition that causes the destruction of the cells responsible for insulin production. Due to this condition, the cells are attacked by the body’s immune system and are unable to function properly. 
  • Type 2 diabetes, is a condition characterised by decreased insulin production and insensitivity of the body’s cells to insulin. Dehydration is particularly problematic for patients with type 2 diabetes since it makes blood sugar control more complicated.
  • Diabetes insipidus is a form of diabetes not linked with high blood sugar levels; it however increases the risk of dehydration as well. It is characterised by the inability of the body to regulate the amount of water within the body. 

The topic of diabetes and dehydration is of concern and relevance to many people. Dehydration can be very dangerous and can lead to kidney failure and diabetic coma in the worst-case scenario. This article aims to raise awareness on the topic and provide insights for those seeking to know more about this condition. 

Recommended level of water intake for people with diabetes

Water is a great ally and resource for a healthy life and to prevent dehydration, especially for people with diabetes. It does not raise blood glucose levels, and it fosters the elimination of more glucose from the blood. For this reason, people with diabetes are advised to drink more often and stay hydrated because they are at a higher risk of dehydration.

The European Food Safety Authority suggests the following as the adequate average quantity of water per day:  

  • Women: 1.6 litres 
  • Men: 2 litres 

There is no consensus on the exact quantity of water that might be needed for people living with diabetes. However, they should consume at least the same amount as non-diabetic people.3


Causes of dehydration

Not drinking a sufficient amount of water, diarrhoea and vomiting, physical exercise, and fatigue are the main causes of dehydration. However, diabetes itself is a cause of dehydration, especially diabetes insipidus. Dehydration is also caused specifically by high blood glucose levels for the reasons mentioned earlier, meaning that having diabetes is indeed a factor exposing an individual to the risk of dehydration.

Dehydration and blood glucose levels

The body tries to remove the excess glucose from the blood through urine. In this way, the kidneys act as filters for the blood, removing water from it. This process makes us thirsty, and if we do not act upon it, we get dehydrated. 

Without drinking water, the kidneys will find it difficult to pass glucose out of our blood through urine. The body will therefore attempt to rely on other sources of water to regulate the sugar level, for example, tears or saliva. This will make us even more dehydrated. 


The main symptoms of dehydration are considered to be headache and sense of dizziness, thirst, dry mouth and eyes, dark yellow-coloured urine, and sleepiness. These symptoms can then develop into more serious ones caused by severe dehydration. Among them, the most common ones are sunken eyes, low blood pressure, lethargy, increased heartbeat and a weak pulse. 

Diabetes thirst

When living with diabetes, thirst and dehydration are part of the equation. However, by taking some simple initiatives such as being careful with drinking water even when not thirsty, at least every hour, one can witness great improvements. 


Drinking an adequate amount of water is the main method to treat diabetes thirst. If the patient is dealing with severe dehydration, the doctor might prescribe electrolytes which could also be low in dehydration. 

People that have diabetes insipidus may be prescribed specific amounts of water per day and may be asked to drink specific fluids containing electrolytes.


Among others, health risks of dehydration include diabetic ketoacidosis and kidney failure. As previously mentioned, dehydration can be associated with, or lead to diabetic coma.

Diabetic ketoacidosis

When ketone levels increase as the levels of glucose in the blood do, it results in ketoacidosis. When ketoacidosis combines with dehydration, this can lead to diabetic coma if not treated in a timely manner.

Kidney failure

The kidneys need fluids to function. A chronic condition of dehydration may lead to impairment of kidneys’ functions and eventually lead to kidney failure if not treated. The risk increases if the person in question already had pre-existing difficulties in kidney function. 

Ways to stay hydrated

If one struggles with drinking water and would prefer to consume fluids from a different source, eating fruit instead can be helpful. For people who simply forget about drinking due to their busy lives, there are apps designed to send a notification reminding the user to drink water every hour.

When to see your doctor

It is advisable to seek the help of a doctor if the symptoms of dehydration start to appear frequently or worse if severe symptoms of dehydration start to appear. 

People diagnosed with diabetes should be careful and attentive in spotting the signs right on time, in order to avoid complications.


Dehydration is one of the symptoms of diabetes, and it is often present during acute complications of the disease. By being aware of the symptoms, the importance of hydration, what negligence can lead to, and when to seek medical help, one can avoid serious complications and foster positive change in their own life by embracing a healthy lifestyle. 


  1. Watts M. Diabetes [Internet]. 2019. People with diabetes have an increased risk of dehydration as high blood glucose levels lead to decreased hydration in the body.; [cited 2022 Nov 26]. Available from: https://www.diabetes.co.uk/dehydration-and-diabetes.html.
  2. Seery C. Diabetes [Internet]. 2019. Normal blood sugar ranges and blood sugar ranges for adults and children with type 1 diabetes, type 2 diabetes and blood sugar ranges to determine people with diabetes.; [cited 2022 Nov 26]. Available from: https://www.diabetes.co.uk/diabetes_care/blood-sugar-level-ranges.html.
  3. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary Reference Values for water. EFS2 [Internet]. 2010 [cited 2022 Nov 26]; 8(3). Available from: https://data.europa.eu/doi/10.2903/j.efsa.2010.1459.
  4. Diabetic ketoacidosis. nhs.uk [Internet]. 2017 [cited 2022 Nov 26]. Available from: https://www.nhs.uk/conditions/diabetic-ketoacidosis/.

Arianna Maviglia

Maastricht University - MSc, European Public Health Governance & Leadership

As a passionate and motivated public health graduate, I believe that good communication is key to improving people's health, and I am committed to finding ways to make medical information more understandable and relevant for different audiences. I have experience in medical writing and a background in political sciences, with a focus on public health and global governance. I am committed to advocating for policies that promote health equity and addressing the root causes of health disparities, enhancing health literacy and promoting scientific communication.

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