When should I check my blood sugar?

Checking Blood Sugar, Doctablet Diabetes 1 Comment

Maybe you have diabetes. It is not too uncommon nowadays. After informing you of this diagnosis, someone in the doctor’s office probably reviewed how to check your blood sugar: They showed you how to put the unused strip into the meter and stick your finger for a small amount of blood— the basics are probably very clear. Sometimes the doctor’s assistant spends so much time talking about how to use the machine that they forget to tell the patient the correct time to check their sugar.


We will cover some general rules about the correct timing of fingerstick blood sugar level measurement. These apply to most people with diabetes.

There are two times that are the most valuable to test for blood sugar:

  • Immediately (or 15 minutes) before a meal


  • 2 hours after a meal

how to check blood sugar: Checking before meals works well

Doctors often simplify this timing by instructing patients to check their sugar level in the blood before meals and at bed time. Why would your doctor prescribe these more simplified instructions? Checking before meals and at bedtime works well because: It is easier to remember. Most people stop what they are doing to eat a meal and are more likely to remember they need to check before than they are to remember 2 hours after eating.

how to check blood sugar: Bedtime is another time.

Bedtime is another time when things slow down and people tend to remember to check their sugar. The simplified meal and bedtime method offers the most information with the fewest number of fingerstick checks. The blood sugar level measurement two hours after eating a meal is not really necessary because of the timing, occurring so closely to the next meal. For example: if a patient checks their blood sugar before breakfast at 9AM, the next check would be due two hours later, at 11AM. If they plan to have lunch at 12 PM and check it 15 minutes before this meal, these last two checks would be very close (within 45 minutes) to each other.

The rule of ALTERNATING:

Another important rule about correct blood sugar level measurement is to ALTERNATE. Changing the time of day when you check is ALMOST AS IMPORTANT AS THE TIME YOU CHECK IT! Think of monitoring your blood sugar like playing a game of hopscotch.

In hopscotch, you land in a different box every time you jump forward. No two jumps are the same as you alternate between landing on one or two feet. You would never win in hopscotch if you kept jumping in the same box over and over again. This is the same idea as checking your fingerstick every morning over and over again, you do not gain very much new information. If each hopscotch jump represents a different day of the week, you can only move forward by alternating the feet you land on. The more variety in the information a doctor reviews, the better they can find and target the issue. In addition to the morning level, there should be values from before lunch, before dinner and at bedtime. In fact. most patients with diabetes have high blood sugars after eating. By just checking the blood sugar while fasting in the morning, patients will miss discovering this problem.

ALTERNATE the time you test for blood sugar.

How often should I be checking my blood sugar?

While the right time to check the blood sugar is similar for most patients, the number of times a patient should monitor their sugar is specific to the individual. If the diabetes is very well controlled and the patient is not on medications that can cause abnormally low blood sugar, the doctor may recommend NOT checking the blood sugar at all. However, if a patient is on insulin injections, checking the blood sugar as often as 3 to 6 times per day is recommended (depending upon the number of injections). Check with your doctor about how often they expect you to monitor based upon your specific situation, but remember the time of day that is correct to check it is still the same (before meals and at bedtime).

Should I bring my glucometer to my visits?

The simple answer is YES! Some medical offices, like those who specialize in diabetes, have the ability to download the information in your meter so it is available for your doctor to interpret in an organized way. Check with your doctor’s office to see if this is possible. Even if it is not, it is useful to have your glucometer at the visit. Many patients get confused as to which machine they have at home. When the doctor prescribes your supplies they need to know the type of meter you have in order to know what type of strip works with your machine. Believe it or not testing supplies are very specific and strips only work with a single type of meter. This is similar to your mechanic knowing your car model so he can order the right parts.

Should I write my blood sugar down?

Keeping a log of your blood sugar is extremely important. The more up-to-date the information is, the more important it is to have it with you during your visit. Be sure that the fingerstick values for the last month are with you. Bringing your doctor just the glucometer and expecting that they can fumble through all the numbers in the machine will likely end up wasting a lot of valuable time. A doctor can scan over a written log and look for patterns much more easily than through a glucose meter. The best types of logs are ones that show the blood sugar horizontally throughout the day, starting in the morning and ending at night. A list from top to bottom can be a little confusing for doctors to interpret because it is more difficult to look for trends at particular times of day. For example, it would be useful for your doctor to know that the fingersticks are high at bedtime but always much lower in the morning.

Your doctor can quickly scan a log that looks like this for patterns and possible problems.

Click on the image to download and print your fingerstick log:

About the Author

Chris Palmeiro D.O. M.Sc.


Dr. Palmeiro is Chairman of Endocrinology at the HealthAlliance of the Hudson Valley, he also serves patients with intellectual and developmental disabilities at the Westchester Institute of Human Development in Valhalla, New York. He has a Masters of Science degree in clinical nutrition and is a diplomate of the American Board of Internal Medicine. His interests within the realm of endocrinology include nutrition support, obesity counseling and the progressive management of diabetes.

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Last Modified: Sep 17, 2018 @ 5:52 pm

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