WHEN DIABETES IS SUSPECTED
If the doctor suspects diabetes, because the patient has been experiencing symptoms like unusual thirst, frequent urination, fatigue, and sudden, unexplained weight loss, the glucose levels of the patient’s blood must be determined. A blood sugar level of 200 mg% or more in a person with the typical symptoms of diabetes confirms the diagnosis.When the symptoms are not as obvious, the doctor may run a fasting glucose test. The blood test is done early in the morning before any food has been eaten. Fasting glucose levels under 115 mg% for an adult, or under 140 mg% for a child, are considered normal. If glucose levels are high, the patient will be tested again, often on another day. (A single high result might be due to a laboratory error.)For adult patients, when the diagnosis is still uncertain, the doctor may administer a glucose tolerance test. First the fasting glucose level is determined, then the patient drinks a measured amount of a concentrated glucose solution. (It tastes so sweet that most people have to struggle to get it all down.) The patient’s blood is then tested again at various times after drinking the liquid to see how quickly glucose levels rise, how high they rise, and how long it takes for them to come down again. These results show how well the pancreas can cope with a sugar load. Too high a rise or too slow a fall may be an indication of diabetes. (In a healthy person, the blood sugar level is usually back down to the fasting level within three hours after a meal.)Once the doctor’s suspicions are confirmed, how does he or she figure out which type of diabetes the patient has? “Together with the results of these tests, the patient’s age and weight often pretty much tell us which type of diabetes it is,” says Dr. Douglas Greene of the University of Michigan Medical Center. “If someone is young rather than old and lean rather than fat, we suspect Type I disease (IDDM) rather than Type II, whereas we suspect Type II disease (NIDDM) if the patient is heavy and getting along in years.” Blood or urine tests for ketones also help doctors make a diagnosis: patients with Type I diabetes often have evidence of ketone buildup, which is much less common in Type II diabetes.*26\268\2*
