Serum glucose, also known as blood sugar, is the amount of glucose or sugar present in the blood. Its measurement is often done to establish the diagnosis of diabetes mellitus. Regular monitoring of serum glucose is also vital in the management and treatment of people with diabetes.
Glucose in the blood comes primarily from food sources, such as carbohydrates. Carbohydrates in the diet are generally broken down into smaller structures called glucose, which are then distributed throughout the body via the blood to be used for energy by cells. As serum glucose rises, the pancreas releases insulin production. Insulin is an important hormone that regulates glucose uptake in cells throughout the body. When insulin is low, as in diabetes and pancreatic cancer, cells do not absorb glucose, and its concentration remains persistently high in the blood.
The usual procedure for testing serum glucose is to perform a fasting blood glucose test. Patients are instructed to fast overnight, that is, not to eat food for at least eight hours. Normally, the concentration of glucose in the blood is 100 mg/dL. A fasting blood glucose between 100 mg/dL and 126 mg/dL is said to put an individual in a stage of prediabetes. Dietary precautions and lifestyle changes are often recommended for people with serum glucose within this range to stop the development of diabetes.
A high level of glucose or hyperglycemia in serum, usually 126 mg/dL and above, is often an indication of diabetes. Other conditions in which serum glucose is also elevated include pancreatitis, Cushing's syndrome, and chronic kidney failure. Too much sugar-rich food and drink can also cause a temporary spike in blood glucose levels. Medications, such as corticosteroids and antidepressants, are among the many types of medications that can also cause hyperglycemia. Symptoms associated with hyperglycemia include increased thirst, frequent urination, and blurred vision.
Hypoglycemia, or a low blood glucose concentration, usually below 70 mg/dL, can also occur. It is mainly seen in conditions such as hypothyroidism and insulinoma, a rare tumor in the pancreas that secretes insulin in large amounts. Symptoms of hypoglycemia include confusion, dizziness, fatigue, and in severe cases, seizures and coma.
Managing high serum glucose, such as that seen in diabetes, often includes lifestyle changes that include regular exercise, eating healthy meals, and avoiding foods that can raise blood sugar. Adequate compliance with daily medications is recommended. Blood glucose tests are also done regularly to monitor the patient's response to treatment.