Confirm the diagnosis
Even if a first test says you're diabetic, a second is advised before deeming the diagnosis official. The initial results may be unreliable if, say, the lab made a mistake or if you accidentally ate or drank before being tested, says endocrinologist John Buse, past president of medicine and science at the American Diabetes Association. Patients aren't supposed to eat or drink before undergoing the fasting plasma glucose and oral glucose tolerance tests. The hemoglobin A1c test, however, which measures average blood glucose levels over three months, can provide an accurate diagnosis even if given soon after a meal or if you have a cold or other infection, which can throw off the results of those other tests. (Despite its strengths, the A1c should still be done twice.) People whose A1c is at least 6.5 are considered diabetic and are often put on medications to lower blood sugar.