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 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 times of day 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 is working.
When should I check my 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
Key times to check your blood sugar
The following summarizes times your doctor may advise you to check your blood glucose.1,2
Fasting or 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 to see how food impacts your blood glucose. For those of you who take mealtime insulin (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 less than 180 mg/dL 1-2 hours after a meal.1
Before meals
Checking at this time is helpful for those who take 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 bedtime
Knowing your number before bed can assist you in screening for low blood glucose (this is an essential consideration if you take insulin or an oral medication that increases your risk for low blood sugar). Your doctor may advise you 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 less than 180 mg/dL according to the American Diabetes Association blood glucose guidelines.1
At 2 am/middle of the night
Overnight blood glucose checks, 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 low blood sugar levels that unknowingly occur overnight.
Additional times to check blood sugar
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 low blood sugar. Monitoring your blood glucose before, during (in particular if exercise is longer than 1 hour), and 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 low blood sugar.
During illness or stress
Illness and/or stress may cause your blood glucose to be higher than average.
Blood sugar can determine treatment options
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
Discuss blood sugar levels with a doctor
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.
How often do you check your blood sugar?
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