Dehydration is a condition in which the body has lost water and blood volume is decreased. Depending on how much fluid the body has lost, dehydration can be classified as mild, moderate or severe. When blood volume is decreased, the concentration of glucose, which is circulating in the blood, increases. Not only does dehydration increase blood glucose levels, but increased blood glucose levels exacerbate dehydration because the body disposes of the excess glucose in the urine, leading to increased water loss.
Dehydration
Vomiting, diarrhea, excessive sweating, vigorous exercise, illness, high temperatures and humidity and too much alcohol consumption can cause dehydration. The symptoms of mild dehydration are thirstiness, fatigue and headache. People who are moderately to severely dehydrated may experience irritability, low blood pressure, rapid heart rate, confusion and potentially, coma and death. Children, elderly people and those with chronic illnesses are more susceptible to dehydration.
Water Solute Balance
The amount of water in the body is maintained by a highly regulated process that involves the thirst center in the brain, the hormone, vasopressin, which acts on the kidneys, and plasma osmolarity. Plasma osmolarity refers to the concentration of solutes, of which glucose is one, in the blood. A higher concentration of glucose in the blood stimulates vasopressin release and kidney reabsorption of water from the urine. These actions maintain water balance and blood volume.
Diabetes and Dehydration
People with diabetes are more susceptible to other causes of dehydration, especially when their blood glucose levels are not managed properly. Commonly, people at the onset of diabetes display symptoms of dehydration. A study in the "Journal of Neuroendocrinology" reports that patients with uncontrolled diabetes and hyperglycemia have impaired regulation of water balance, contributing to diabetes-associated dehydration.
Hyperglycemia-Induced Dehydration
People with uncontrolled diabetes may have markedly elevated blood glucose levels. The American Diabetes Association, or ADA, reports that persistent glucose levels above 600 mg/dL can cause a hyperglycemic hyperosmolar state, which can be life-threatening. If this state is untreated, severe dehydration will result, leading to seizures, coma and death. Another cause of severe dehydration is ketoacidosis, which more commonly occurs in type 1 diabetics. In the condition of ketoacidosis, glucose levels and ketones are markedly elevated, again leading to excessive urination and severe dehydration.
Treatment
Mild dehydration usually resolves with increasing fluid intake. Severe dehydration is a medical emergency and requires immediate treatment. Patients with severe hydration are treated with intravenous fluids and electrolytes. Patients with hyperglycemic hyperosmolarity or ketoacidosis are additionally administered insulin.
