Insulin Safety Center

Understanding Blood Sugar

Glucose is an important source of energy for the body. The term “blood sugar” is commonly used to describe the amount of glucose in your blood. Blood sugar can be measured at any time of the day. It is important for your blood sugar to stay in a healthy range. Blood sugar levels are measured in milligrams per deciliter (mg/dl). The goal for most people with diabetes is to keep their blood sugar below 140 mg/dL.

At home, people with diabetes can check their blood sugar by poking their fingertip for a drop of blood and using a blood sugar meter. Another way to check blood sugar is by using a continuous glucose monitor (CGM). A CGM is a device that is attached to your body and uses small sensors to measure your blood sugar. The information is sent to an application (app) on a mobile device. A blood sugar test can also be done in the laboratory. If your doctor orders this type of test, it will require you to get a vial of blood drawn.

Types of Blood Sugar Tests:

There are four common types of blood sugar tests:

1) Random Blood Sugar Test....a snapshot of your blood at anytime

A random blood sugar test (RBS) is a sample of your blood sugar at anytime. It does not matter if you recently ate food or did not. It can be taken at anytime of the day. A normal RBS is 125 mg/dL or less.

2) “Fasting” Blood Sugar...a snapshot of your blood sugar control on an empty stomach

If you have not eaten for 8 hours or more, this is called a "fasting" blood sugar. In people without diabetes, a "fasting" blood sugar is usually between 70 and 110 (mg/dL). Diabetes is diagnosed when the fasting blood sugar is 126 mg/dL or higher.

3) "Post-Prandial" Blood Sugar...a shapshot of your mealtime blood sugar control

If you ate a meal about 2 hours ago, this would be called a "2-hour post-prandial" blood sugar. A post-prandial blood sugar test is done to see how a person's body responds to the sugar and starch in a meal. The goal for a "2-hour post-prandial" blood sugar for most nonpregnant adults with diabetes is less than 180 (mg/dL).

4) A1C...an album of your blood sugar control

There is a way to measure your long-term blood sugar control. It's called an A1C (also known as the hemoglobin A1C) test. This test measures the average of your blood sugar over the past 2-3 months. The results of the test are given as a percentage. A normal A1C for people without diabetes is below 5.7%. The goal for most adults with diabetes is an A1C that is less than 7%.