How Often Should I Check My Blood Sugar?

Have you ever wondered how often you should be monitoring your blood glucose and at what times of day the you should be checking? As a diabetes educator (CDE), I am often asked both of those questions.

The frequency of blood glucose monitoring can range from a few random checks throughout the week to up to 6 to 10 checks each day. The time(s) of day that blood glucose is monitored will depend on your current treatment plan. Self-monitoring of blood glucose (SMBG) allows you and your physician to assess how your current treatment plan (i.e. lifestyle and medication) is working.

What factors affect how often and when to check blood sugar?

The frequency and timing of SMBG should take into consideration the following:

  • Your current diabetes medications (no medication, oral medication, insulin, and/or other injectable medications)
  • Your current level of control
  • Your risk for having a low blood sugar
  • Your personal goals
  • Insurance coverage of test strips

When should I check blood sugar?

The following is a list of times you may be advised to check your blood glucose: 1,2

Fasting/before breakfast

This information is helpful for adjusting long acting insulin as well as adjusting some oral diabetes medications.

The American Diabetes Association recommends a fasting blood glucose level of 80-130 mg/dL.1

1-2 hours after a meal

Knowing your number after a meal allows you see how food impacts your blood glucose. For those of you who take meal time insulin (i.e. rapid acting insulin), this information will allow you to see if your insulin dose was well matched to your food intake.

The American Diabetes Association recommends a blood glucose of < 180 mg/dL 1-2 hours after a meal.1

Before meals

Checking at this time is helpful for those of you taking rapid acting insulin at meals to assess how well your insulin dose at the previous meal matched your food intake.

The American Diabetes Association recommends a pre-meal blood glucose level of 80-130 mg/dL.1

Before bed

Knowing your number before bed can assist you in screening for a low blood glucose (this is an important consideration if you take insulin or an oral medication that increases your risk for a low blood sugar). Your doctor may advise to eat additional carbohydrates at bedtime if your blood glucose is below a specified number.

If you have a snack after your dinner meal, checking your blood glucose before bed will allow you to see how that snack impacted your blood sugar. If it has been 1-2 hours since your snack your blood glucose should be < 180 mg/dL according to the American Diabetes Association blood glucose guidelines.1

At 2 am/middle of the night

Overnight blood glucose check, while inconvenient, are typically done to screen for hypoglycemia (low blood glucose) as it is more common to not feel a low blood sugar overnight and to sleep through a hypoglycemia event. If you wake up with a headache or a stomach ache it may be due to a low blood sugar that unknowingly occurred overnight

Before, during and after exercise

Exercise typically causes blood glucose to go down. If you take insulin and certain oral medications, exercise may increase your risk for a low blood sugar. Monitoring your blood glucose before, during (in particular if exercise is longer than 1 hour), as well as after exercise can help you see the impact of exercise on your blood glucose and help screen for hypoglycemia.

Before driving

Checking at this time allows you to better ensure your blood glucose is at a safe number before getting behind the wheel.

After consuming alcohol

Alcohol may increase your risk of having a low blood sugar.

During illness or stress

Illness and/or stress may cause your blood glucose to be higher than normal.

Recommendations – standard of care in diabetes

The 2018 standards of care in diabetes have recommended the following:

“Most patients using intensive insulin regimens (multiple-dose insulin or insulin pump therapy) should perform self-monitoring of blood glucose (SMBG) prior to meals and snacks, at bedtime, occasionally postprandially, prior to exercise, when they suspect low blood glucose, after treating low blood glucose until they are normoglycemic, and prior to critical tasks such as driving.” 2

“When prescribed as part of a broad educational program, SMBG may help to guide treatment decisions and/or self-management for patients taking less frequent insulin injections or noninsulin therapies.”2

Take away

  • Make sure to speak with your physician about how often you should be checking your blood sugar and at what times of day or week checks should be done.
  • Don’t forget to ask your physician: “What should I do with all this information?” Your overall control will likely not improve unless you know what to do with the glucose numbers you are seeing!
  • If you are uncertain how to use your meter, ask to meet with a diabetes educator for additional training.
This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Type2Diabetes.com team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.
View References
  1. American Diabetes Association. Checking Your Blood Glucose 2018. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/checking-your-blood-glucose.html. Accessed September 30, 2018.
  2. American Diabetes Association. Glycemic Targets: Standards of Medical Care in Diabetes—2018. Diabetes Care. 2018; 41(1): S55-S6. 4

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