A1C Estimator instructions for use

Using one of the A1C Estimator forms, Simple or Full, enter a minimum of 8 sets of data to complete a RUN cycle. A set of data includes your blood sugar meter reading (mg/dl), the checking time (hours) and some comments showing your meals and activities. You can skip the comments if you want. 3 or more RUN cycles are required to complete one MONTH cycle which can approximate your lab A1C for a period or three months. There is no need to poke your fingers 8 times a day to get all these sugar readings. Some of them could simply be familiar readings from your past experience with different meals and activities. The readings must be ordered as follows: before meals (also called Pre-prandial), 2 hours after meals (also called Postprandial), bedtime and wakeup times as shown in the A1C Estimator default form. Again, you don't need to complete a RUN cycle in one day, you can do this in different days including days with lower, moderate, and higher numbers. Bedtime and Wakeup readings must always be entered in the form. Bedtime/Wakeup times are your usual times to go to bed and wake up.

Usually, the highest blood sugar occurs 2 hours after you start eating. If your past experience shows that between the time you start eating and 2 hours later your sugar readings move in the same direction say, 125, 145, 195, you may not need to enter intermediate sugar values within the 2-hour interval (A1C Estimator will do this for you). In this case, you can use the Simple Form which only requires 8 readings to complete a RUN instead of the Full Form. Remember, keep your post meals glucose below 180 mg/dl for an A1C lower than 6.5.

It is always good to know what a particular sugar reading might be after having a certain meal or just any food that you like. You can create a table (food | activity | time | glucose) and use these readings with the A1C Estimator instead of poking your fingers. Once you have achieved a MONTH pattern completed you can update this pattern with just a few new sugar readings measured with your glucose meter and see in what direction your A1C goes. Obviously, if it goes in the wrong direction (high) you should follow up with a few days of low carbs diet and some exercise.

  • RUN - this is a cycle of blood sugar readings, checking times and comments over one or more days. Blood sugar measurements collected during a RUN are shown under the VALUE column. A minimum of 8 measurements are required to complete a RUN cycle.
  • MONTH - this is the time necessary to complete a minimum of 3 to 5 RUN cycles, normally one calendar month. As shown above, besides your glucose meter readings you can also include familiar known sugar readings from the past which will considerably shorten the MONTH time. However, the more real measurements you use the closer you get to the lab A1C.
  • AG (average glucose) - this is the average sugar readings for one RUN cycle. It is expressed in mg/dl (milligrams/deciliter) units. A1C Estimator calculates these averages by taking into account the fact that blood sugar can go up or down between measurements.
  • A1C - this is the conversion of the AG average units (mg/dl) to A1C units (percentage number rounded to one decimal). It is important to understand that the A1C calculated for one RUN cycle (RUN A1C) is NOT the actual lab measured A1C. Only the total A1C calculated for more than 3 to 5 fully completed RUN cycles (MONTH A1C) can estimate the lab A1C.

  • Click a RUN number.
  • Fill out the 8 measuring times under TIME, the 8 sugar readings under VALUE, meals and other comments under MEALS/ETC if any. We recommend using the "2-hour" default TIME profile from A1C Estimator Simple Form. Click 'Save RUN data' to save data.
  • Click the 'Calculate A1C' button or any 'A1C' field in the form to calculate your A1C or the average glucose AG for the RUN. The current date and time are also added. You can switch between A1C and AG displayed units by clicking the 'Change units' button. Click 'Save RUN data' to save the RUN data.
  • Do this for 3 to 5 RUN cycles to complete one MONTH cycle period.
  • When the 3 to 5 RUN cycles are complete click 'MONTH A1C' to get the estimated A1C and average glucose AG for the MONTH.
  • To save the entire form data and text click 'Save to file'. On a Windows computer this is equivalent to Ctrl + s which opens the Windows File Picker. Give the file a name, select a folder and click Save.

The A1C Estimator uses a series of carefully selected blood glucose measurements expressed in mg/dl, averages these numbers and calculates an estimated A1C. It is based on multiple studies that show that there is a direct correlation between the average blood glucose (AG) measured over an arbitrarily period of time expressed in dl/mg and the percentage of glucose measured in a sample of blood unit (A1C).

The interest in expressing the state of diabetes in a simple way spawned a lot of scientific studies during the years. Finally, the experts realized that it makes more sense to present the test results as a small, easy to remember number. This is why A1C, a one decimal percentage number is used instead of larger numbers representing the average blood glucose. This method is based on a large population study proving that there is a direct correlation between the average blood glucose and the lab measured A1C. You can read this study at Translating the A1C Assay Into Estimated Average Glucose Values. Below are some details and conclusions of this study:
"This work was supported by research grants from the American Diabetes Association and European Association for the Study of Diabetes. Financial support was provided by Abbott Diabetes Care, Bayer Healthcare, and many other institutions. The large population allowed us to demonstrate that the relationship between A1C and AG was consistent across prespecified subgroups..."
"The tight relationship and the consistency of the relationship across different subgroups suggest that for many, if not most, patients with diabetes, there are no important factors that affect the relationship between mean glucose levels and A1C..."
"The current results support the reporting of the measured A1C as eAG..."
"The current study provides a relatively complete assessment of day-to-day glycemia and establishes a strong enough relationship between A1C and AG levels to justify a direct translation from measured A1C to an easier-to-understand value that is in the same units as fingerstick monitoring..."

Another interesting study: Measurement of Hemoglobin A1c
This study shows how A1C is actually measured, methods of separating the glycated from the nonglycated hemoglobin and quantify the amount of each and a little bit of history of how scientists found out that the HbA1c predicts the development of microvascular and macrovascular complications of diabetes.

  • You are provided with an easy way to calculate and forecast one of the most important factors of diabetes care, the A1C. This calculated number directly corelates with your average glucose over an arbitrarily selected period of time (not one day, one week, or one month). The calculated A1C is also an estimated value of your lab measured A1C, directly related with your meals, activities and lifestyle.
  • You can easily play around with your sugar numbers in the A1C Estimator forms and see the impact to your estimated A1C.
  • You always have a record of what was good or bad for your sugar so you can make corrections in the future.
  • All the data displayed on the A1C Estimator page is saved on your computer or smart phone, not on a server or in the cloud. Your privacy is always guaranteed.
  • You can show your doctor the collected data, the results and your progress in an organized manner.
  • The A1C Estimator is compatible with all computers, operating systems and smart phones.

  • The A1C Estimator provides a clue as to what your next A1C result might be, but don’t be surprised if they aren’t a perfect match. The good news is that most people had results within 0.3 percentage points, meaning the two values should still be close. However, the results are directly related to how many pre and post meal points along with sleep and wake up points you provide.

The A1C Estimator uses a series of carefully selected blood glucose measurements expressed in mg/dl (AG) and calculates a randomly moving average instead of the regular average of a series of numbers. This approach could approximate the unpredictable variations of the blood glucose content between meals. The A1C calculated this way may have slightly different values for the same numbers entered in the form and it this is more pronounced for large difference between two consecutive numbers.

  • AG (average glucose) - this is the average of your sugar readings per RUN. A1C Estimator calculates these averages by taking into account the fact that blood sugar can go up or down between measurements.
  • A1C - this is the conversion of the AG average units above to A1C units. It is important to understand that the calculated A1C per RUN is NOT the actual lab measured A1C. Only the MONTH A1C calculated for 3, 5 or more fully completed RUN cycles can estimate the lab A1C.
  • RUN - this is a cycle of 8 measurements over two or more days. Blood sugar measurements collected during one RUN are shown under the VALUE column. 8 measurements are required to complete a RUN cycle.
  • MONTH - this is the cycle necessary to complete a number of RUN cycles (3, 5 or more). If you are doing 2 measurements per day then, to complete one RUN cycle you need 4 days and to complete 5 RUN cycles (one MONTH) you need 20 days. If you do 4 measurements a day, you only need about two weeks to estimate your lab A1C and so on. You can also include "no measured data" by using familiar known sugar values from the past which will considerably shorten the MONTH time. Note however, that the more real measurements you use the closer you get to the lab A1C.
  • TIME - the time in hours you checked your blood sugar.
  • VALUE - these are the blood sugar meter readings or some familiar readings from the past for the specified times. As mentioned above, you can also use 'unmeasured' sugar readings that you are usually getting for certain types of known meals and activities. This should be done with caution!
How to fill out the A1C Estimator form
  • RUN (1 to 8 or 1 to 16): click the number under RUN to select the current RUN.
  • TIME (AM/PM): enter the time you checked your sugar levels. Time must be entered in ascending order and it should always include the bedtime and wakeup time. Use the default times provided by A1C Estimator: breakfast, 2 hours later post breakfast, lunch, 2 hours later post lunch, dinner, 2 hours later post dinner, bedtime, wakeup. However, intermediate measurement times and values can also be used. Checking times must be entered in hours only with a minimum difference of 1 hour. Empty cells are allowed only on the Full Form..
  • VALUE (mg/dl): these are the blood sugar meter readings for the specified times. Only SI units _milligrams / deciliter are supported. User should convert other units to mg/dl.
  • A1C/AG: these are the calculated A1C or the average glucose AG for the selected RUN. You can select what units to display by using the "Change units" button.
  • DATE: shows the Date and Time you calculated your A1C or AG.
  • Calculate A1C: calculate the A1C for the RUN. This is done by calculating the average value of the sugar readings for the RUN (AG) and converting to A1C units.
  • Save RUN data: save the form data to your computer. This includes the times, readings, meals and comments, A1C/AG , dates.
  • MONTH A1C/AG: calculate the equivalent A1C for the MONTH. MONTH includes a number of RUN cycle, usually in one calendar month.
  • Change units: switch the display between A1C (percentage, rounded to single digit) and AG (mg/dl) units.
  • Disable alerts: disable/enable audio alerts usually when an error occurs.
  • Save to file: save the entire A1C Estimator form to a file in your computer.
  • Load file: Loads a previously saved A1C Estimator form and text to the browser.
  • Print this page: print the A1C Estimator page on your printer (tested with the Chrome browser on Windows computers).
  • Copy RUN Data: copy the current RUN data (TIME, VALUE, MEALS) to another RUN. Select the RUN to copy from, click 'Copy RUN data' then click the RUN to copy to.
  • Clear RUN: delete selected data for the current RUN.
  • Clear All: delete all A1C Estimator data stored in your computer.

  • Bagels, muffins, tortilla, corn
  • White bread
  • Sweets including sweet juices and fruits
  • Ice cream
  • French fries
  • Chicken, fish, other lean meats
  • Eggs
  • Vegetables, salads
  • Multigrain bread, less than 10g carbs per slice
  • Apples, cherries (other fruits, not too sweet)
  • Red wine (?)


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Get familiar with A1C Estimator

Click RUN 1 to load an example showing some checking times (TIME), some arbitrarily selected sugar readings (VALUE) in dl/mg and the recommended mealtimes (MEALS/ETC). Note the pre and post mealtimes as well as the bedtime and wakeup time. Click 'Calculate A1C' to calculate the equivalent A1C for this RUN.

Click 'Save RUN data' to save this RUN data including the A1C and Date.

Now change the Post Breakfast sugar value to say, 280 (a heavier breakfast), then click 'Calculate A1C' to calculate your A1C for the new RUN. See what happens... Your equivalent A1C for the RUN went up.

Click RUN 1 to get back to the initial numbers.(if you don't save data you can get back to the old values this way)

Now change all the Post Breakfast, Post Lunch and Post Dinner numbers to 280 (probably a full American breakfast with toast and butter, a loaded baked potato for lunch and a cruise type dinner). Click 'Calculate A1C" and ...oops your A1C for this RUN when up by more than 25%. And note that 280 mg/dl is not necessarily an extremely high blood sugar value.

If this was a real case, probably the only way to get back to a lower A1C is to lower your carbs and sugar in addition to more exercise for the next RUN.

You can play with the numbers by entering different average glucose values taken from your blood sugar meter. Say your meter gives you weekly averages. Click 'MONTH A1C' and enter 5 or more of these averages under the AG column. Scroll down the page and click again 'MONTH A1C' to calculate your total average glucose and equivalent A1C for those weeks. If the checking times are as the A1C Estimator recommended times, the resulting A1C should fairly estimate your real lab A1C.

If you want to change the measurements units click 'Change units". You can switch between glucose units (mg/dl) and A1C units (percentage).

If you want to copy data (TIME and VALUE) from one RUN to another, click the RUN you want to copy from then click the RUN you want to copy to.

If you want to erase a RUN data, click the button 'Clear RUN'.

To print the page press 'Ctrl + p' or select "Print" from your browser menu. To save the page to a file in your computer press "Ctrl + s" on a Windows desktop computer.