Sugar can dehydrate you if it reaches very high levels in the blood. This can happen if you are diabetic, take certain medications or have an infection or certain diseases of organs. If your kidneys start producing more urine to try to eliminate the sugar and you lose enough fluid, you can dehydrate.
Under normal circumstances, the pancreas responds to higher sugar levels by producing more insulin, a hormone that allows your body's cells to take glucose of blood to obtain energy. This returns blood sugar levels to normal. In type 1 diabetes, the pancreas produces little or no insulin. In type 2 diabetes, the body loses its sensitivity to insulin, although the pancreas produces it. Many diabetics use some form of insulin therapy to avoid high blood sugar levels.
Other causes of hyperglycemia or high blood sugar include injury or physical trauma, steroid therapy or IV nutrition therapy that contains a large amount of glucose. If you have kidney disease, liver disease and pancreas, you can also develop hyperglycemia. In some cases, the production of insulin decreases. In others, the liver produces too much glucose. If hyperglycemia occurs, it can lead to excess urination and dehydration.
Your doctor may order several tests to check for hyperglycemia, such as various blood sugar tests that are taken before and after a meal or monitored throughout of two or more hours. Because diabetes is such a common disease, your doctor will probably want to rule out that condition early on. Depending on your symptoms, you may or may not order other tests at the same time, for the detection of other diseases.
The symptoms of dehydration are dry mouth, decreased urination, lethargy, low blood pressure, rapid pulse, loss of skin elasticity and shock. Drinking small amounts of fluid may be enough if you have mild dehydration. There are also special electrolyte solutions available that contain balanced amounts of salt and sugar. You may need IV treatment in a hospital if you are moderately or severely dehydrated. Severe dehydration can cause seizures, brain damage and even death.