How Often Do You Need to Check Your Blood Sugar?

Blood sugar checks are essential for the diagnosis and treatment of every form of diabetes.

“Glucose monitoring is critical for preventing short-term and long-term complications of diabetes,” says Jessica Pius-Nwagwu, RN, an associate director of dissemination and implementation for the American Diabetes Association. “It provides real-time feedback on glucose fluctuations, identifies low and high glucose levels both with risks, and informs medical adjustments.”

There’s more than one way to measure your blood sugar.

Blood Sugar Meter or Continuous Glucose Monitor (CGM)

A blood sugar meter reveals your blood sugar level at the moment the test is taken.

Doctors may encourage others, especially those who use insulin to manage their type 1 or type 2 diabetes, to test their blood sugar multiple times throughout the day, including before and after meals and exercise. These checks can show how food and lifestyle choices affect diabetes management and can help determine how much insulin they need and how often.

Marilyn Tan, MD, a clinical associate professor of medicine specializing in endocrinology, gerontology, and metabolism at Stanford University in California, explains that CGMs measure changes in the interstitial fluid that contains blood sugar, rather than blood sugar itself.

“So readings may lag and may be less accurate at extremes of glucose [levels],” Dr. Tan says.

A1C Test

Typically, a doctor administers an A1C via a blood draw or finger prick, with a sample sent to a lab to process results. Over-the-counter, at-home A1C tests are available. Ask your doctor if they are appropriate for your situation.

Pius-Nwagwu says that people with type 2 diabetes not on insulin should do a fasting blood sugar test daily, in addition to an A1C test that usually occurs quarterly. She adds that you should check with your doctor about the best frequency for your situation.

Tan says that frequency may depend on factors that include:

• How controlled your diabetes is
• Medications such as sulfonylureas that lower blood sugar

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• Availability of test strips

She adds that checking blood sugar after meals may be helpful if you have type 2 diabetes without using insulin, but random blood sugar checks otherwise are usually unnecessary.

If your type 2 diabetes treatment requires insulin, your doctor may tell you to test your blood sugar several times a day. This is in part to avoid the threat of low blood sugar (hypoglycemia), a potentially dangerous side effect of insulin use.

• Before meals
• Before bed
• Occasionally after meals
• Before, during, and after exercise
• When you suspect low blood sugar
• After treating low blood sugar
• Before and during critical tasks, such as driving

“Typically, someone on multiple daily injections of insulin (basal bolus) needs closer monitoring than someone on once-daily, long-acting insulin,” Tan says, “especially given that there are multiple opportunities to adjust dosing throughout the day and also more opportunities to overdose or underdose on insulin.”

If you have type 2 diabetes and are on insulin, Pius-Nwagwu recommends testing A1C at least twice a year and quarterly if you are not meeting your A1C goals, regardless of the type of insulin.

“Even once-daily, long-acting insulin can lead to hypoglycemia, so all of these patients can benefit from a CGM,” she says.

“For those with established prediabetes, an A1C test every three to six months is reasonable,” says Tan, who adds that the frequency depends on how close test results are to type 2 diabetes.

Given a nearly constant need for accurate blood sugar measurements and an enhanced risk of hypoglycemia, the American Diabetes Association recommends that people with type 1 diabetes use CGMs.

“For healthcare providers, more data is helpful,” says Tan, adding that more tests can guide treatment decisions and monitor blood sugar fluctuations.

• Routine blood sugar monitoring is a vital part of diabetes management and can prevent complications.
• Testing options include fingerprick tests, continuous glucose monitoring (CGM), and A1C tests that measure longer-term averages.
• If your type 1 or type 2 diabetes requires insulin treatment, you may require as many as 10 blood sugar tests each day, and could benefit from even more by using a CGM.
• Always talk to your doctor about which blood sugar monitoring plans will work best for your specific condition.