The hemoglobin A1C test is a simple blood test that measures the average level of glucose in your blood over the last three months. Hemoglobin is a protein in our red blood cells, and small amounts of glucose will naturally bond to it. The A1C test measures the amount of this hemoglobin bonded with glucose. You may already be familiar with a fasting blood glucose test which measures your blood sugar levels after you don't eat for 8 to 12 hours. With the A1C test, you do not need to fast because what you eat on the day of the test won't affect the results.
Although testing fasting blood glucose levels is common, it only gives blood sugar at one single point in time. That's why tests are often repeated or additional tests are ordered. The A1C test instead gives an average of blood sugar levels over 3 months, which may be a better indicator of just how well (or not) blood sugar is being managed. For example, someone could eat heavily throughout the day and have high blood sugars due to large meals and carbohydrate-laden foods... but then eat lightly in the evenings, allowing blood sugar levels to gradually fall overnight.
Normal (non-diabetic): 4% to 6% - some doctors recommend keeping A1C below 5.5%.
Prediabetic: 6.1% to 6.5% - having prediabetes increases your risk for developing type 2 diabetes.
Diabetic: above 6.5%.
A common recommendation for diabetics is to keep A1C below 7%, and closer to 6% if possible (your doctor will set a target A1C that is individualized for you). Continued high A1C can lead to serious complications of diabetes, such as eye problems and heart disease or kidney disease.
To achieve a lower risk of diabetes, you can lose weight if you are overweight (even a small weight loss is beneficial), engage in regular aerobic exercise, and plan your meals with the help of a dietitian or nutritionist who can create a sustainable eating plan for you. Even if you are not currently showing signs of diabetes, the numbers don't lie - taking action immediately will give you a better chance to get the numbers under control and perhaps stave off type 2 diabetes.
If you blood tests show prediabetic A1C numbers, ask your doctor for help. He or she may suggest medication if you have a family history of diabetes. In many cases a glucometer may also be suggested so that you can see how various foods and exercise impact your blood sugar levels. However, regular visits to your doctor - typically once every 3 months - are still recommended, along with repeat tests of A1C and fasting blood glucose levels.