Dehydration occurs when the body loses large amounts of fluids, causing the body to reabsorb fluid from the blood and other body tissues. It is natural for the body to lose more than 10 cups (2.5 liters) of water every day simply through basic life processes such as perspiration, breathing and elimination of wastes. The body also loses electrolytes (including potassium, sodium and calcium) that maintain the balance of fluids in the body.

Normally, a person is able to replace the fluids lost through eating and drinking. However, in some cases more water and salt is lost than is replaced. This causes the body to dry out, or dehydrate. On average, water makes up 60 percent a person’s body weight. Thus, dehydration can seriously affect health.

Several factors and conditions can exacerbate the loss of fluid that leads to dehydration. These include:

• High glucose (blood sugar) levels. Excess glucose in the bloodstream causes the body to become dehydrated. For this reason, people with diabetes are at a high risk for dehydration.
  
  
• Fluid loss. Sources of fluid loss include excessive urine output (polyuria). This symptom is commonly associated with diabetes. It also includes vomiting, diarrhea, excessive perspiration and fever.
  
  
• Inadequate intake of fluids. Failure to drink enough fluids is often the result of feeling unwell because of illnesses and conditions such as nausea, mouth sores, sore throat or loss of appetite.
  
  
• Illnesses. A wide range of conditions ranging from the flu to food poisoning can cause dehydration, especially if diarrhea or vomiting is involved.
  
  
• Medications. Diuretics are perhaps the best-known of the drugs that can cause dehydration. The diabetes drug metformin, a biguanide, is also of concern, according to the American Diabetes Association. Supplements such as creatine can also cause dehydration.
  
  
• Diet. Sodium, caffeine and alcohol can lead to dehydration. Researchers have found that dehydration can be a side effect of low-carbohydrate diets.
  
  
• Environment. Airline travel and other dry environments can encourage dehydration.