To diagnose diabetes, health care providers run blood tests to determine the patient's blood sugar level. Since type 2 diabetes, a condition often diagnosed in adulthood, does not always cause symptoms, so sometimes the blood sugar test is the only indicator of the condition. Type 1 diabetes is usually diagnosed in childhood. Type 1 diabetics do not produce any insulin, so they often become quite ill before diagnosis. Non-diabetics can develop type 2 diabetes due to weight gain or diet.
Blood Sugar
Healthy adults convert digested food into energy by releasing glucose, a sugar, into the bloodstream. The pancreas releases a hormone called insulin that helps the body use glucose for energy by moving it into the muscle, fat and liver cells. When the body does not produce enough insulin or resists its effects, as in the case in diabetes mellitus, glucose does not move efficiently from the bloodstream and, over time, it damages the heart and other organs unless the patient takes steps to regulate it through diet, exercise and medication.
Fasting Blood Sugar
To measure the fasting blood sugar level, blood is drawn at least eight hours after the patient's last meal. A normal blood sugar level equals less than 100 mg/dL, according to MedlinePlus. An individual with a fasting blood sugar level between 100 and 125 mg/dL has impaired fasting glucose (IFG), or pre-diabetes, according to the American Diabetes Association. A fasting blood glucose level of 126 mg/dL or higher indicates diabetes.
Glucose Tolerance Test
A less common test for diabetes involves administering 75 g of glucose by mouth and drawing the patient's blood twp hours later. A normal blood sugar level is less than 140 mg/dL. If the level is between 140 and 199 mg/dL, the patient has impaired glucose intolerance, also called pre-diabetes. A level of 200 or greater indicates diabetes. To make a firm diagnosis of diabetes, the doctor performs a second test on another day.
Blood Sugar Level Fluctuations
Many factors may temporarily increase an individual's blood sugar level, even in non-diabetics. These factors include trauma, stroke, heart attack, surgery and drugs such as corticosteroids, dextrose, epinephrine, diuretics, estrogen, aspirin and certain antidepressants. On the other hand, certain medications may reduce blood sugar including acetaminophen, alcohol, anabolic steroids, monoamine oxidase inhibitors (MAOIs) and oral diabetic medications.
References
- The Merck Manuals Online Medical Library: Diabetes Mellitus
- "Diabetes Care;" Standards of Medical Care in Diabetes---2009; American Diabetes Association; January 2009
- MedlinePlus; Diabetes Mellitus; May 10, 2010
- MedlinePlus; Glucose Test - Blood; May 23, 2010
- MayoClinic.com; Prediabetes; Jan. 21, 2011
