Blood Glucose Tests: What You Should Know

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When you have diabetes, you may use a blood glucose test to check the level of your blood glucose, or blood sugar.

If you take insulin, you may use a blood glucose tester, or glucometer, a few times a day. If you take non-insulin medication, you may only need an A1c test, which is done at your doctor’s office, every 3-6 months. An A1c test is a blood test that shows your doctor the average of your blood glucose levels over 3 months.

Blood Glucose Tests as You Age

As you get older, your doctor may change how you monitor your blood sugar.

“The targets your doctor wants you to aim for may change based on your age or other health factors,” says Patrice Conrad, a senior diabetes specialist at Priority Health in Grand Rapids, MI.

“Older patients are at a higher risk of having low blood glucose with certain medications, such as insulin and sulfonylureas,” says Jocelyne Karam, MD, director of the Division of Endocrinology at Maimonides Medical Center in Brooklyn, NY.

You may also have a higher risk of low blood glucose if you have certain conditions, like kidney, liver, or heart problems, or if your appetite gets smaller.

To prevent low blood sugar, or hypoglycemia, your doctor will want you to monitor your levels closely with a blood glucose test.

What Blood Glucose Tests Do

Your blood glucose levels go up and down throughout the day. They may rise after you eat, then fall after you go a long time without eating.

Your doctor will give you a target range for your blood glucose level. If it goes too low, you can have problems functioning and thinking well. If they go too high, it may cause problems for your body over time.

By using a glucometer, you can check your levels and make adjustments to keep them in a healthy range.

Types of Blood Glucose Tests

There are different types of blood glucose tests.

Fingerstick blood glucose test. With this test, you poke your finger with a lancet to get a small drop of blood. You put the blood on a strip, then the glucometer tells you what your blood sugar level is at that moment.


Continuous glucose monitoring device (CGM). With a CGM test, you put a sticker-like patch, or glucose sensor, on your skin. It gives you a readout on your smartphone or another device like an insulin pump. “It can measure and transmit glucose readings every 5 minutes, 24 hours a day,” says Karam. You may replace the sensor every 7-14 days.

“The benefit of CGM is you can see what your blood sugars are all the time, best of all, without poking,” says Conrad, a registered nurse. A CGM is helpful if you have multiple insulin shots during the day or if your levels vary a lot.

How to Choose the Right Test for You

The best test may be the one that’s easiest for you to use.

“There are talking meters for people who may not see well, and some may have bigger numbers for those with limited vision,” says Conrad. Some have backlighting, to make them easier to read. Others store your readings so you can share them with your doctor by downloading them.

“Older patients who have difficulty sticking their fingers, but still need to have frequent glucose readings, can benefit from glucose sensors,” says Karam. But you need some technical skill to use a CGM device, so they may not be right for everyone.

Talk to your doctor or pharmacist about which test may be best for you.

When to Check Your Blood Sugar

Your doctor will tell you how often to test your blood glucose levels, and if you need to make changes as you age.

“If you’re on insulin, they’ll often want you to check before meals and bedtime,” says Conrad. “If they’ve been running high or low, they’ll want at least that many, if not more, tests.”

If your numbers have been running at or near your target most of the time and you’re not taking insulin with meals, your doctor may recommend testing less often.

“Patients with type 2 diabetes treated with diet alone, or medications that don’t cause low blood glucose, might only need to check with a fingerstick a few times a week,” Karam says.

If you have changes in medications, medical conditions, or appetite, your doctor may recommend adjusting your testing schedule to avoid low blood sugar.


Keep Your Numbers on Target as You Age

You can take steps to make sure your blood glucose levels stay at a healthy target range. “Lots of things affect your blood sugar. Some you have control over, some you don’t,” Conrad says.

Here’s what you can do to keep your levels on track.

  • Eat healthy most of the time.
  • Be as active as you can.
  • Manage your stress the best that you can.

  • Check your blood sugar levels as often as your doctor recommends.
  • Take your medication on time, every time.



Patrice Conrad, registered nurse; senior diabetes specialist, Priority Health, Grand Rapids, MI.

Jocelyne Karam, MD, director, Division of Endocrinology, Maimonides Medical Center, Brooklyn, NY.

American Diabetes Association: “The Big Picture: Checking Your Blood Glucose.”

Health In Aging: “Diabetes Care & Treatment,” “Diabetes Unique to Older Adults.”

Johns Hopkins Medicine: “Diabetes: What You Need to Know as You Age.”

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