The sugar in your blood, also known as blood glucose, is a major source of energy for your body, especially your brain and nervous system. Not only do the brain and nervous system rely on glucose for energy, but according to Lab Tests Online, they cannot function properly if the levels of glucose in your blood fall below a certain level. The glucose in your blood comes from the food you eat, the breakdown of glycogen and synthesis in your body.
Physiology
Two pancreatic hormones, insulin and glucagon, are responsible for maintaining a constant level of glucose in your blood. When you eat carbohydrates, your body breaks them down into glucose, which enters your blood through your small intestine. The rise in blood glucose signals the pancreas to release insulin, which carries glucose to your cells so that they can use it for energy. Once glucose is brought to your cells, your blood sugar levels decrease.
If your blood sugar levels get too low, the hormone glucagon signals the liver to release glycogen, which is the storage form of glucose. Glycogen is broken down into glucose, raising your blood sugar levels.
Disruptions in Blood Sugar
For most people, the glucose/insulin feedback mechanism helps keep blood sugar levels fairly stable. Some people, such as those with diabetes, experience abnormalities with this mechanism. If this mechanism is disrupted in any way, the body tries to compensate by increasing insulin production or excreting glucose through the urine. This can lead to dangerous increases in blood sugar, known as hyperglycemia, or life-threatening decreases in blood sugar, called hypoglycemia. If you are diabetic, it is important to monitor your blood sugar levels regularly.
Normal Blood Sugar Levels
Your doctor can test your glucose response in different ways. A fasting blood glucose test measures the amount of glucose in your blood after an extended period of time without any food. A normal fasting glucose level falls between 70 and 99 mg/dL. If your fasting blood glucose falls between 100 and 125 mg/dL, it is considered impaired fasting glucose and levels that exceed 125 mg/dL are categorized as diabetes.
Your doctor can also test your response to glucose with an oral glucose tolerance test, or OGTT. During this diagnostic test, you will drink a solution that contains 75g of glucose. After two hours have passed, your doctor will draw your blood and measure the amount of glucose it contains. If your blood sugar level is less than 140 mg/dL, you have normal glucose tolerance. Levels that exceed 140 mg/dL indicate impaired fasting glucose.
Considerations
While diabetes is the most common cause of abnormal blood sugar levels, several other conditions can cause disruptions in the way your body handles glucose. Elevated blood sugar levels can occur as a result of trauma, heart attack, stroke, kidney failure, pancreatic cancer, inflammation of the pancreas, certain medications, hyperthyroidism and excessive food intake.
Decreased blood sugar levels may be caused by excessive alcohol intake, liver disease, underactive pituitary gland, hypothyroidism, insulin overdose, tumors on the pancreas and extended periods of time without food.
References
- Montana State University: Alcohol Messes With Your Blood Sugar Levels
- Lab Tests Online; Glucose; March 22, 2011
- "Nutrition and You"; Joan Salge Blake; 2008
