By definition, diabetes is an elevated blood glucose level that persists over time. Since type 2 diabetes may occur with no symptoms, it is possible to have the condition for years without noticing. Over time, symptoms will develop and they may become severe. You may want to have your blood sugar tested as part of your yearly physical examination by a physician, especially if you have one or more risk factors for developing diabetes. The American Diabetes Association recommends being tested yearly beginning at age 45, especially if you are overweight.

Diagnosing type 2 diabetes

Fasting blood glucose test

After fasting overnight (at least 8 hours) a blood test can be performed to check your blood sugar. If your blood glucose level is 126 milligrams per deciliter (mg/dL) after fasting for 8 hours on two separate testing occasions, you have diabetes. If your blood glucose is between 100 and 125mg/dL, this is considered prediabetes, which is a risk factor for developing diabetes.

Random (non-fasting) blood glucose test

If you have a blood sample taken - regardless of how long it has been since you last ate - and your non-fasting blood glucose is higher than 200 mg/dL, the doctor will suspect diabetes. This is especially true if you are having other diabetes symptoms such as increased thirst and urination. A fasting blood glucose test must be done to confirm the results.

Oral glucose tolerance test

The oral glucose tolerance test examines how well your body metabolizes sugar after it is introduced into your body. After fasting overnight, the doctor will provide you with a sample of sugary liquid to drink. Then, a blood sample is taken every 30 to 60 minutes after you drink the solution for 2 to 3 hours. Diabetes is diagnosed if your blood glucose level is higher than 200 mg/dL after 2 hours. If your blood glucose is between 140 and 200 mg/dL it is considered “impaired glucose tolerance” or prediabetes.

Glycated hemoglobin (A1C) test

If you’re diagnosed with diabetes, your doctor may also suggest a glycated hemoglobin (A1C) test. This test gives a measure of the average blood sugar level over the previous 1 to 3 months. The A1C test looks at the oxygen-carrying molecules called hemoglobin that are found in red blood cells and determines how much sugar they have been exposed to. The doctor takes a blood sample and examines what proportion of your hemoglobin molecules have sugars attached to them (how many are “glycated”). The higher the proportion of glycated hemoglobin in the blood, the more sugar there has been in the blood over the past few months. A target A1C result is 7 percent or less.