hormonal and metabolic disorders
Diabetes Mellitus (DM)
Diagnosis of Diabetes Mellitus
Measuring the level of glucose in the blood The diagnosis of diabetes is made when people have abnormally high levels of glucose in the blood. Doctors do Screening for Diabetes on people who are at risk of diabetes but have no symptoms. People may have type 2 diabetes and no symptoms, so it is important for people with risk factors to have recommended screening tests. Doctors check blood glucose levels in people who have symptoms of diabetes, such as increased thirst, urination, or hunger. Additionally, doctors may check blood glucose levels in people who have disorders that can be complications of diabetes, such as frequent infections, foot ulcers, and yeast infections. To accurately evaluate blood glucose levels, doctors usually use a blood sample taken after people have fasted overnight. Diabetes can be diagnosed if fasting blood glucose levels are 126 mg/dL (7.0 mmol/L) or higher. However, it is possible to use blood samples taken after people have eaten. Some elevation of blood glucose levels after eating is normal, but even after a meal the levels should not be very high. Diabetes can be diagnosed if a random (not done after fasting) blood glucose level is higher than 200 mg/dL (11.1 mmol/L). Doctors can also measure the level of a protein, hemoglobin A1C (also called glycosylated or glycolated hemoglobin), in the blood, which reflects the person's long-term trends in blood glucose levels rather than rapid changes. Hemoglobin is the red, oxygen-carrying substance in red blood cells. When blood is exposed to high blood glucose levels over a period of time, glucose attaches to the hemoglobin and forms glycosylated hemoglobin. The hemoglobin A1C level blood test is reported as the percentage of hemoglobin that is A1C . Measurements of hemoglobin A1C can be used to diagnose diabetes when testing is done by a certified laboratory (not by instruments used at home or in a doctor's office). People with a hemoglobin A1C level of 6.5% or more have diabetes. If the level is between 5.7 and 6.4, they have prediabetes and are at risk of developing diabetes. Another kind of blood test, an oral glucose tolerance test, may be done in certain situations, such as screening pregnant women for Gestational diabetes or testing older adults who have symptoms of diabetes but normal glucose levels when fasting. However, it is not routinely used for testing for diabetes because the test can be very cumbersome. In this test, people fast, have a blood sample taken to determine the fasting blood glucose level, and then drink a special solution containing a large, standard amount of glucose. More blood samples are then taken over the next 2 to 3 hours and are tested to determine whether the glucose in the blood rises to abnormally high levels. 