Blood sugar log: your readings, kept on your own device

Before you check

There are different kinds of meters, and the Centers for Disease Control and Prevention (CDC) says to ask your health care team to show you how yours works. Its steps for a finger-stick test:

• Make sure the meter is charged and ready to use.
• Wash your hands with soap and warm water, and dry them well, before each test.
• Massage or shake out your hand to get blood into your finger.
• Prick your finger with the lancet. Squeezing from the base of the finger, gently place a small amount of blood onto the test strip.
• Place the strip in the meter. After a few seconds, the reading will appear.
• Record the result, with a note about anything that might have affected it.
• Put the lancet and the strip in a trash container. Do not share testing equipment, especially lancets, with anyone, even family members.

The CDC also says that cold hands can make it hard to get enough blood (warm them before you wash them), and that test strips can be damaged by moisture, humidity or extreme temperatures, so keep their container tightly closed. It says your doctor will tell you when and how often to check. We read this on the CDC page Monitoring your blood sugar on October 6, 2026.

The numbers this page uses

Under each reading the page says where it sits next to numbers the CDC publishes. All are in mg/dL:

• Before meals: 80 to 130. After meals (1 to 2 hours later): below 180. The CDC gives these as the recommended ranges for most people with diabetes who are not pregnant, and adds that your target range may be different based on your age, health status and diabetes management plan, and to always follow your doctor’s recommendations specified for you.
• Below 70: low. The CDC says that at this level you need to take action to bring it back up.
• Below 55: severely low. That is the number on the CDC’s page about treatment; its page about low blood sugar says below 54. This page uses 55, so a reading of 54 gets the stronger words.
• 250 or above: the level at which the CDC says a person with diabetes needs to check their blood sugar every 4 to 6 hours and check their urine for ketones.
• Above 180: the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a federal institute, calls a level above 180 high blood glucose for most people with diabetes, and says to talk with your health care team if you often have high or low levels. Looking back counts your readings above 180 and below 70.

A reading with no “before a meal” or “1 to 2 hours after a meal” attached, and between 70 and 249, gets no range: the CDC page gives none for bedtime or other moments. We read these on the CDC pages Monitoring your blood sugar, Low blood sugar (hypoglycemia), Treatment of low blood sugar and Diabetic ketoacidosis, and the institute’s page Managing diabetes, on October 6, 2026. They are those organizations’ words, shortened; we added no numbers of our own.

When a reading is low or very high

Keep a reading below 70, or one of 250 or above, and a box opens under the button with the CDC’s steps. They are written for people with diabetes. In short:

• Below 70, the 15-15 rule: have 15 grams of carbs, wait 15 minutes, check again, and repeat while it is still less than 70. The CDC lists half a cup of juice or regular soda, a tablespoon of sugar, honey or syrup, or 3 to 4 glucose tablets.
• Below 55: you may not be able to treat it yourself. The CDC says injectable glucagon is the best way to treat it, and to contact a doctor for emergency treatment immediately after an injection. The NIDDK says to have the people around you call 911 right away after giving glucagon, or if there is no glucagon emergency kit at hand. We read that on its page Low blood glucose (hypoglycemia) on the same day.
• 250 or above: check again every 4 to 6 hours and check your urine for ketones. The CDC says to go to the emergency room or call 911 right away if your blood sugar stays at 300 or above, your breath smells fruity, you are vomiting and cannot keep food or drinks down, you are having trouble breathing, or you have several signs of diabetic ketoacidosis.

If your own care team gave you a plan for lows, highs or sick days, their plan is the one to follow.

How it works

• A reading asks for the number, the day and the time. When it was taken, a few things about the moment and a note are optional.
• My readings lists them, newest first, each next to the CDC’s numbers. Change puts one back in the boxes; Remove takes it out.
• Looking back gives the average of the last 7 days and the last 30, readings before and after meals apart, the lowest and highest, how many were below 70 or above 180, and a bar for each recent reading.
• Print my sheet makes a table of your last 24 readings with empty rows to fill in by hand.

What this page can’t do

• It measures nothing. It only knows the numbers you type, and a typing slip looks the same to it as a real reading.
• It does not diagnose diabetes, prediabetes or anything else, and is not treatment. Setting a reading next to a published number is not a diagnosis.
• It does not say what your numbers ought to be. Your care team may have given you a different target from the CDC’s ranges, and that target is the one that counts.
• It is no reason to change a medicine or an insulin dose. The CDC says not to make any changes to your medicines without talking to your doctor.
• It takes mg/dL only. A meter that shows mmol/L (numbers like 5.6) uses a different unit, and this page does not convert it.
• It does not know about pregnancy or about children. The CDC’s ranges are for people who are not pregnant; ask your own care team which numbers matter for you or your child, and when to call.
• It is not a continuous glucose monitor and cannot read one. It has no alarm for a low in the night.
• It cannot remind you. It has no alarm and sends no message.
• The log does not move to another phone or computer by itself. Print it, download it, or use My data on this device to carry a backup across.

Where the idea comes from

Writing readings down is ordinary advice. The CDC says that most meters save your results, that some use an app on your phone, and that you can keep a written record if you would rather not use a phone; it also says you may want to keep notes about anything that might have affected a reading. Many meters and phone apps keep such a log on a company’s computers. This page does the arithmetic and keeps nothing anywhere but here. It is not any clinic’s official form, and no doctor, nurse or diabetes educator has looked at it.