Insulin

• During normal digestion, glucose makes its way into the bloodstream, where it is carried to cells throughout the body to serve as fuel. Excess glucose must be neutralized, however, and the pancreas secretes insulin into the bloodstream to take care of the extra sugar. Unfortunately, both genetic factors and a long-term high-sugar diet can affect the body's ability to regulate its own glucose level, leading to diabetes and other conditions.
  
  

Glucose Tolerance

• The glucose tolerance test is a simple procedure designed to measure the body's ability to use and store glucose. After an eight-hour fast, your doctor will have you drink a solution of glucose and water, and will draw blood to test glucose levels at various points afterward. Typically the first sample is drawn after an hour, as under normal circumstances blood sugars peak an hour after eating. Further samples will be taken to monitor your body's use and reduction of the remaining sugar.
  
  

Insulin Resistance

• The most common condition that interferes with this process is insulin resistance. This is usually a precursor to type 2 (or adult-onset) diabetes, and occurs when a high-sugar diet results in a chronic overload of insulin in the bloodstream. Eventually this leads to the body's cells becoming resistant to the insulin's effects, and causes excessive levels of glucose to remain in the blood long after eating. If glucose levels peak after you drink the glucose solution, and remain high, it can be a sign that your body is becoming resistant to insulin and requires medication to help you control blood sugar levels.
  
  

Reactive Hypoglycemia

• Another condition that can be revealed through the glucose tolerance test is reactive hypoglycemia, in which blood sugar levels dip abnormally low. In this case the pancreas secretes too much insulin into the bloodstream, which can reduce glucose to dangerous levels and cause light-headedness, dizziness or even life-threatening symptoms.
  
  

Results

• If you show abnormal insulin reactions through the glucose tolerance test, your doctor will prepare a plan to deal with your pre-diabetic or diabetic condition. This may involve diet modification, an increase in exercise, medication or all three.