Understanding FPG, PPG, and A1C

When it comes to diabetes, there are a lot of numbers and initials to remember. So, maybe your health care provider has mentioned these terms to you and you weren’t exactly sure what they meant. Or, maybe they are brand new to you. Either way, understanding what FPG, PPG, and A1C mean can be very important when you are trying to reach your blood sugar goals.

 

A1C measures how well your blood sugar has been controlled over the past 2 to 3 months. It also gives you an idea of how well your overall diabetes care plan is working. Your health care provider will be checking your A1C on a regular basis. 

FPG is your “fasting plasma glucose (sugar)”. This is your blood sugar when you have been “fasting” (not eating) for at least 8 hours. You may be checking this in the morning when you wake up. 

PPG is your “postprandial plasma glucose (sugar)”. This is your blood sugar level about 1 to 2 hours after you eat. It measures blood sugar spikes that happen after you eat. 

 

What do these numbers have in common? Your A1C tells you how well your PPG and your FPG have been controlled over the past 2 to 3 months. Or, to put it another way, A1C control=FPG control & PPG control. 

Why are these numbers important? To help measure how you are doing with your diabetes care, your health care provider will set a goal for what your A1C should be and will measure A1C every 2 to 3 months in most cases or at least twice a year if you are meeting your treatment goals. 

Your A1C gives you a good idea of your blood sugar control over time. In general, your goal is to keep your blood sugar level as close to your goal as possible. This can help reduce the risk of some diabetes-related problems, like problems with the eyes (diabetic retinopathy), and the nerves in places like the hands and feet (neuropathy). Reducing the risk of some of these problems and getting your blood sugar under control is the goal of your diabetes care plan. 

According to the American Diabetes Association (ADA), most adults with diabetes should aim for an A1C of less than 7%. The American Association of Clinical Endocrinologists (AACE) sets goals that are even lower (less than 6.5%). This is because the risk of diabetes problems increases as A1C goes up. Your A1C goal may be more or less than these numbers based upon what your health care provider thinks makes the most sense for you. For instance, the ADA A1C guideline for children and adolescents younger than 18 years of age is less than 7.5%. 

Recommended Targets:

ADA AACE
A1C <7% <6.5%
FPG 80 to 130 mg/dL <110 mg/dL
PPG <180 mg/dL <140 mg/dL

How many times you check your blood sugar per day will depend on your health care provider’s instructions. Many people with type 2 diabetes check their blood sugar in the morning before they eat breakfast (FPG) and perhaps 1 or 2 other times per day. Some people, especially people with type 1 diabetes who are trying to keep their blood sugar as close to the level of someone without diabetes as possible (tight control), may check up to 8 times a day. 

The way PPG control works can be complicated, but the closer you get to your A1C goal, the bigger the effect PPG has on your A1C. 

So, maybe you are checking your morning blood sugar before breakfast (FPG) and it is within the range your health care provider set for you. Sometimes this number is fine, but it turns out your A1C is still higher than it should be when you get it checked a few weeks later. At that point, you may need to also start checking your after-meal blood sugar (PPG). It is possible that blood sugar spikes after you eat may be preventing you from getting to goal. If it turns out your PPG is high and you do need help controlling your PPG, adding a mealtime insulin like NovoLog® may help you get to your A1C goal.

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