Glucose

Glucose (Blood Sugar) is a form of sugar and your body’s main source of energy. During digestion, your body breaks down carbohydrates from foods like bread, fruit, vegetables and dairy products into a variety of sugar molecules, one of which is glucose. Shortly after you eat, glucose is absorbed directly into your bloodstream, but it is unable to enter your cells and tissues without the help of insulin.

Insulin is a hormone produced by your pancreas, an organ located just behind your stomach. The pancreas is constantly producing insulin. When your blood sugar increases after you eat, your pancreas also increases insulin production. This extra insulin “unlocks” your cells so that sugar in your bloodstream can enter them, providing your body with energy and maintaining a healthy blood sugar level. If you have more glucose than your body needs, the excess is removed from your blood and stored in your liver. Then, whenever your body is running low on fuel, it can tap into this resource to maintain steady energy between meals and snacks.

It’s important that you know your glucose level because it can indicate serious health concerns if outside the normal range, most notably diabetes.

How often should I have my glucose checked?
According to the American Diabetes Association, everyone should have their glucose checked once they turn 45. If the test results are within a normal range, you should have it rechecked every three years. If your glucose levels are borderline or high, you should have a fasting blood sugar test performed once every year.

However, because type 2 diabetes is becoming more prevalent among younger people, including children, McDowell Hospital strongly recommends having your glucose level checked starting in your twenties. Even if your glucose levels are normal, these results can be used to compare with future glucose test results.

How do they check glucose?
To determine your glucose level, you will have to undergo a simple blood test; however, there are several different types of blood glucose tests that can be used. The one most commonly performed is the fasting blood glucose test. With this test, your doctor or healthcare professional will ask you to not eat or drink anything (except water) for at least eight hours. After eight hours of fasting, blood will be drawn from a vein in your arm and sent off to a lab for analysis. This is usually the first test your doctor will use to check for diabetes.

The second kind of test is a random blood sugar test, or a casual blood glucose test. This test is often a part of a routine physical exam. It does not take into account the last time you ate, and for this reason may indicate higher glucose levels than a fasting glucose test. However, if you are healthy, your glucose level should not vary that much throughout the day.

A third option is a two-hour glucose tolerance test. This test measures how your body responds to sugar. Your doctor or healthcare professional may have you drink a sugary liquid and then wait two hours before drawing a blood sample, or he or she may simply perform the test two hours after your last meal.

Another kind of test is used for women who are pregnant to determine if they have gestational diabetes. This test is called an oral glucose tolerance test or glucose challenge test. It involves fasting for six hours, then drinking an extremely sugary liquid. Your blood sugar will then be tested every hour for three hours. If your blood sugar rises significantly and doesn’t return to normal by the end of the third hour, you may have gestational diabetes.

A glycated hemoglobin test, or hemoglobin A1C test, is another kind of glucose test that measures how well people with diabetes are managing their blood sugar levels over a two- to three-month period.

Once you receive your glucose test results, your glucose will be measured in either millimoles per liter (mmol/L) or, more commonly, milligrams per deciliter (mg/dL) of blood.

What is a healthy glucose level?
Because there are so many different kinds of glucose tests, there are different ranges for healthy blood sugar depending on which test is performed. If using a fasting blood glucose test, a normal range is between 70 mg/dL and 100 mg/dL. Borderline high glucose, often called prediabetes, is between 100 mg/dL and 125 mg/dL. A fasting blood glucose level cannot alone indicate the onset of diabetes, but a level higher than 125 mg/dL coupled with another symptom can be a strong indicator of type 2 diabetes. Symptoms for diabetes include increased thirst or appetite, frequent urination, weight loss or blurred vision. Consult the tables below for the ranges of glucose levels for other glucose tests.

Fasting Glucose

70 mg/dL to 99 mg/dL		Normal
100 mg/dL to 125 mg/dL		Prediabetes
≥ 126 mg/dL		Diabetes

Random Glucose (no fasting beforehand)

< 100 mg/dL		Normal
100 mg/dL to 199 mg/dL		Prediabetes
≥ 200 mg/dL		Diabetes

2-hour Glucose

< 140 mg/dL		Normal
140 mg/dL to 199 mg/dL		Prediabetes
≥ 200 mg/dL		Diabetes