BG Testing

When diagnosed as a diabetic, it becomes mandatory to test your blood sugars at various times during the day. Ideally the tests should be carried out when (1) Fasting (FA) the first thing in the morning upon waking up. (2) Before meals (BL/BD) (3) Postprandial or after meals (PL/PD) (4) Before and/or after exercise (EX). (5) Randomly (RA) during anytime in the day.

I keep getting a lot of queries on BG tests, testing methods and related questions. I'll try to throw light on some of the things that are important and should be kept in mind during testing. Obviously, testing has to have purpose. Even a cheap home test should tell you something that you want to know. It must reveal some meaningful insight into your 24 hour BG profile.

First, let's begin by talking about meters. There are many companies who have introduced scores of meters in the market. This business is also gaining momentum like the cell phone business, with companies introducing newer models every few months. With an ever expanding consumer base the business is now worth billions of dollars. By law, meters are allowed to be +/- 20% off accuracy. A more accurate system would be cumbersome to manage in terms of size and costs. Hence we make do with the next best. At least meters now are very handy, inexpensive and some Nano models can be carried around in the pocket. But, meters can only keep you informed of your BG “range” and not the exact number at a given time. As the BG level rises, so does the error margin in the accuracy.

Laboratories test for BG out of the blood plasma. Plasma is the watery part of the blood, while home meters test the “whole” blood, which consists of the plasma + everything else (mostly red blood cells). Science tells us that there is a difference between BG of the plasma & BG of whole blood. Some estimates put this at 20 mg/dl, others at 12%, but my feeling is that even this difference varies at differing levels. The inbuilt software in the meter converts your whole blood reading into the plasma BG and then displays it. Since the circulating blood within the body is not homogeneous, the BG number from different parts of the body will also differ. Try taking two readings from two different fingers, one from each hand and see the difference for yourself. BG also changes from moment to moment, it is not a static number, as with all the other health parameters and markers in the body.

Strips are coated with reagents and these are also highly susceptible to corruption by the environment, especially heat. Keep them in a cool place in the house, but not the refrigerator. The meter that I use works by checking for the color change in the strip with IR light before and after the blood is applied and calculating the BG based on the color change. Use strips before the end of expiry date, but sometimes they do work pretty well even beyond.

Wash your hands before every test. Doctors may use an alcohol swab to wipe your finger before pricking, but soap and water works just as fine. If you are the only user of your “lancet” (the pricking device) there is no need for the needle to be changed very frequently. Sometimes I forget to change my needle even after months of use. After extended use the needles do tend to get blunt and will tell you when it is time to change. Do not use your needle for anyone else and do not use the needle used by anybody else. Do not starve the strip for blood. Give it the drop of adequate size. If you have difficulty in getting a good blood flow out of your fingers, try snapping them a few times before the blood draw, or try jerking the hand rapidly, a few times before the prick.

Coming to the tests themselves, as I wrote above, every test ought to have a purpose. Let me tell you how, what and why I tested in the initial stages of my diabetes education. I would test (1) FASTING (the first thing upon waking up) (2) BEFORE every meal to know if I had reached my base line BG before I put any food in my mouth and make it go up again. (3) AFTER meals I would test at 30, 60 & 120 minutes to see what “that” food was doing to my BG. For that I usually had to limit food menus to a single item or a combination of max 2 things at a time. (4) I would check for the effect of EXERCISE on my BG before and then 30 and 60 minutes after the work out. I would check for different forms, duration and intensity of exercise. (5) I even checked the various combinations of foods and exercise put together. (6) Sometimes I checked at RANDOM times just for the heck of it.

If you can predict your BG to within +/- 3 points, it means that you are getting a hang of your own system and becoming your own master bit by bit. When testing like that, it would be quite OK to carry out 15-20 tests a day. “Obsessive” for sure, but you must know your system, before you can begin to treat it. Once enough data has been collected and your BG profile becomes predictable, you need not test aggressively anymore.

If you happen to test like that, you will need a good spreadsheet or logging system to record all that data. Because you have to collate it and then analyze it, for it to have any meaning. If any of you need, I could send you a sample of my excel sheet to help you further.

The take home lesson from all of this is that "The meter is your best friend". It will answer most of your questions. If you want to take control of your blood sugar & take charge of your life, "test, test, test."