Your body needs glucose to make the energy that allows you to think straight, keep your heart beating and your muscles healthy, and much more. With the help of insulin, your cells absorb glucose from your bloodstream. The amount of glucose in your blood typically depends on when and how much you last ate.
Blood Sugar Metabolism
All the cells in your body convert glucose to energy to fuel many different processes. Your cells depend on insulin, a hormone secreted by your pancreas, to help move glucose from your blood, across the cellular membrane, into your cell where it is disassembled and used to create energy. High blood sugar is a result of a disconnect in this process as a result of insufficient insulin secretion, reduced cellular insulin sensitivity or a combination of the two conditions.
Fasting Blood Sugar
The most common test of blood sugar is the fasting blood glucose test. To prepare for this, you cannot eat anything starting at midnight the day of your blood draw. A normal fasting blood glucose level is between 60 and 110 mg/dL. A normal fasting blood sugar level means your body is able to properly metabolize sugar and move it into the cells, while also keeping some sugar in circulation. A fasting blood glucose level of 126 mg/dL or greater on at least two occasions is used to diagnose diabetes mellitus.
Casual Blood Glucose Test
Another way health care providers measure blood glucose regulation is using a random or casual blood glucose test. If a patient has classic signs and symptoms of diabetes, a doctor may order this test to check the person's casual blood sugar. A normal casual blood sugar level is less than 200 mg/dL. A casual blood sugar level of 200 mg/dL or above, in addition to symptoms of diabetes, can be used to diagnose diabetes mellitus.
Oral Glucose Tolerance Testing
One way to measure a person's fasting blood sugar and their ability to metabolize sugar is the oral glucose tolerance test, otherwise known as the oral glucose challenge. For this test, a person drinks a liquid containing a known concentration of glucose; the health care provider measures the person's blood sugar before and after drinking the solution. The normal blood glucose range depends on the amount of glucose in solution. For a 75-g glucose solution, the normal blood glucose range is 60 to 110 mg/dL before drinking the solution, less than 200 mg/dL one hour after drinking the solution, and less than 140 mg/dL two hours after drinking the solution.
References
- National Institute of Health - MedLine Plus; Glucose Tolerance Test; 2010
- "Present Knowledge in Nutrition"; Eighth Edition; Barbara Bowman; 2001
