Glucose serum is more commonly referred to as blood sugar, and it refers to the concentration of sugar, or glucose, in the bloodstream. The carbohydrates you eat are converted to glucose, which is the human body’s primary source of energy. If glucose levels are too high or too low overall, health problems result, the most prevalent of which is diabetes.

The Role of Insulin

The amount of glucose in the bloodstream is regulated by a hormone called insulin, which is secreted by the pancreas. The role of insulin is to transport glucose out of the bloodstream and into the body’s cells, where it is either converted to energy or stored for later use. Eating and drinking stimulate the pancreas to produce insulin. Glucose levels in the bloodstream vary throughout the day, rising when sugar is ingested and dropping as insulin removes the sugar from the bloodstream.

Normal Blood Sugar Levels

Normal fasting glucose serum or blood sugar levels range from 70 to 110 milligrams per deciliter (mg/dL) of blood. Blood sugar may rise as high as 180 mg/dL following a meal, but it should be neutralized within two hours thereafter. A person is considered to be diabetic if the glucose serum concentration is 126 mg/dL or higher after fasting (not having had anything to eat or drink for the previous six to eight hours).

Types of Diabetes

There are two types of diabetes. In type I, the pancreas produces little or no insulin. In type II, the pancreas produces insulin, but the cells develop a resistance or immunity to it, such that they no longer respond to insulin as they should. According to the Merck Manual of Medical Information, type I diabetes accounts for only about 10 percent of all cases of diabetes, and it’s usually diagnosed at a young age, whereas the prevalence of type II diabetes increases with age.

Other Causes of High Blood Sugar

High blood sugar levels are referred to as hyperglycemia. While diabetes is the most frequent cause, other illnesses, including Cushing syndrome, hyperthyroidism, pancreatitis and pancreatic cancer, can also cause high blood sugar. Blood sugar can temporarily rise when the body is subject to severe stress as well, including trauma, heart attack, stroke or surgery. Some prescription drugs also cause a rise in blood sugar.

Causes of Low Blood Sugar

Lower-than-normal blood sugar levels are referred to as hypoglycemia. Symptoms of low blood sugar include dizziness, confusion and profuse sweating, and glucose must be administered immediately to remedy the situation. Conditions that can cause hypoglycemia include hypopituitarism, hypothyroidism and, in people with diabetes, combining too much insulin with too little food. Some prescription drugs can also lower blood sugar.