Diabetes Care Tips
Blood Glucose Monitoring

Print version of the article by Lahle Wolfe, Islets of Hope, 02/24/2006
Located at:  www.isletsofhope.com/diabetes/care/glucose_testing_tips_1.html


Contents

Section 1

  • About Glucose Monitoring and Glucose Meters
  • Terms to Be Familiar With
  • Lancet and Lancing Device Tips
  • "Less-Pain" Finger Sticks
  • Quick Summary of Glucose Testing Tips
  • Important Tips for Accuracy
  • Special Care Tips for Children

Section 2

  • Glucose Meters:  features and how they work
  • Alternative Testing Sites
  • Why should I test my blood glucose?
  • When should I test my blood glucose?
  • Meter Accuracy
  • Non-invasive blood glucose monitoring devices

    Section 1

    About Glucose Monitoring and Glucose Meters

    Blood glucose monitoring is a way of testing how much glucose is in the blood (glycemia).  Hypoglycemia means low blood glucose, hyperglycemia refers to high blood glucose, and normoglcyemia indicates normal blood glucose levels.  In the United States, blood glucose is measured in mg/dL (miligrams per deciliter).  In most other countries, blood glucose is measured in mmol/l.

    Blood glucose meters measure how much glucose is in a given blood sample.  Where the sample comes from (fingers, toes, forearms, ear lobes) will affect test results.   A test strip is placed inside a blood glucose meter (you can ONLY use test strips designed for your particular meter). A drop of blood is then placed on the strip.  Blood reacts with hemicals in the test strip causing a small electronic pulse to be sent into the meter which then calculates the level of glucose in the blood sample and shows the result in a digital display   

    Lancet and Lancing Device Tips

    You do not have to use the lancing device that came with your test kit.  As long as the lancing device you are using draws sufficient blood for your meter you can use anyone that you want.  Not all lancing devices are equal.  Generally, the smaller the drop of blood the less pain involved.  If you choose one that does not draw sufficient blood you will have to squeeze (or "milk") you finger for more blood.  Most people, children in particular, find the hard squeezing more painful than a larger needle, or slightly deeper setting.

    • Depth Setting - Start out on the lowest possible setting.  The deeper the needle penetrates the more blood is drawn, but this will also increases pain.
       
    • Changing Lancets - You do not have to change lancets with every finger stick.  However, the needle does dull with each use.  Duller needles = more pain and you may have to up the depth setting to draw a blood sample.  Many people who test 4 or more times per day change out their lancet once or twice a day at breakfast or bedtime.
       
    • Cleaning Your Lancing Device - Your lancet device should be soaked in rubbing alcohol at least once per week or anytime it is exposed to questionable germ sources.  If it falls into the toilet (yes, this has happened to me, along with an insulin pump) it is better to just throw it away.  You can put most lancing devices (remove the lancet first) in the dishwasher or steam-based toothbrush cleaner to sterilize it.  Do not microwave or boil your device; you will ruin it.
       
    • Lancing Device Safety - Be sure that only one person uses any particular lancing device.  While blood droplets are tiny, producing less blood than a playground scrape, there is always the concern of disease transmission if more than one person uses a lancet.  Be sure to explain to children that they should never prick other people.  In 2005 there was a lot of bad PR about the safety of children with diabetes in public schools when a young girl took her diabetic mother's lancing device to school and pricked many of her classmates.  The students ended up having to be tested for AIDS. When one of the children that was pricked was found to be HIV positive there was, understandably, a lot of parent anxiety.
       

    IOH Tip:  Almost all children (and many adults) fear needles of any sort.  If your child is newly diagnosed it will take time to adjust to the many pricks each day.  It is helpful if you practice on yourself first.  Children may appreciate that you too are going through the same thing and it is a good way to see what hurts and what does not.  (See "Less-Pain" Finger Sticks tips below.)  

    You might also contact your local Juvenile Diabetes Research Foundation Chapter.  Many of JDRF's chapters offer free meters, books, and even an adorable stuffed bear (Rufus of Rudy) to comfort children newly diagnosed with diabetes.   The bears have hearts on their paws, bums and tummies -- places children have to take shots and finger sticks.   

    "Less-Pain" Finger Sticks

    Once, my 10-year-old (who should know better) called me in a panic with a blood glucose reading over 400 mg/dL.  But when she washed her hands, ridding them of the remains of a sugary snack she had eaten earlier, her glucose was normal.  Because of the disparity between 400 and normal I did a third check which confirmed her blood glucose was in fact, normal.  To have administered insulin to treat a 400 reading would have created a medical emergency.  This brings me to my first tip (because repeating sticks causes more pain):

    • Make sure fingertips are clean and dry.  Although many doctors recommend alcohol pads for convenience they can dry out the fingertips making it harder to draw blood.  Also, alcohol, if not totally dry, will prohibit the blood from "beading" so that it can be easily applied to the test strip and may cause stinging.  It is better to simply wash hands with warm water and soap.  The idea behind hand cleanliness has little to do with being sanitary issues because finger infections from lancets is rare.  But foreign substances (food, juice, chemicals, dirt) can pollute the blood sample and provide false readings.  

      In a pinch I pour bottled water (which I always keep in the van for such purpose) over my child's hands to clean them. Disposable hand wipes and sanitizers can produce false readings.  Although many people do use them without complaint, many parents prefer plain water in a pinch over hand sanitizers.  Again, the issue has more to do with ensuring nothing on the hands will interfere with, or alter the results of blood glucose testing, rather than a serious concern for infection (I see doctors cringing....)
       
    • Where NOT to stick fingers - Always try to avoid pricking the finger on the pad where the most nerve endings reside.  This not only induces unnecessary pain but is also not the best "bleed" site on the finger.
       
    • Prick fingers on the sides, a little bit away from the nail (too close to the nail hurts!). This is where the most blood vessels are and the fewest nerve endings.  Smaller fingers bleed better than larger, calloused ones, and the thumb often has the thickest skin.  Using all the fingers and thumb are fine, but you may need to adjust the depth setting for fingers with calluses or thicker skin.
       
    • Stopping the blood After A prick - Again, rubbing alcohol serves to both dry out skin and cause stinging and it really is not necessary.  Here is where you can use an alcohol-free disposable hand cleaner to clean hands and apply pressure if needed.  Sometimes finger sticks continue to bleed, especially on tiny fingers. 

    I keep small gauze pads in my daughter's test kit, insulin pump pouch, or in my purse to apply pressure for what she calls a "gusher."  But Elizabeth much prefers to simlply apply pressure herself or (now mom cringes) plunging her finger into her mouth for a second.  While this may work, it can be disconcerting to other people, especially to parents and school officials.  

    Teach your child how to use a dry gauze pad (cut into small pieces) or cotton ball (which I find "shed" fibers that can stick to the skin) to stop bleeding and reassure other folks.  Make sure anything with blood gets tucked away discretely or disposed of in a sanitary place like a sharps or biohazardous waste container.     

    Quick Summary of Glucose Testing Tips

    • Make sure hands are clean and dry.
       
    • Have everything ready to go.  Prepare meter to receive blood droplet and then perform the finger stick.
       
    • Hold hands down to let blood flow into fingers - keeping hands below heart level.
       
    • You can trying rubbing, massaging, or gently milking fingers prior to finger sticks for better results.
       
    • Running hands under warm water also helps increase blood circulation to the fingers -- just make sure fingers are dry.
       
    • Stick fingers on the sides, not the pads.  If using alternative sites pinch or slap the area first.
       
    • Do not immediately attempt to "milk" or apply pressure to increase blood flow as this will actually have the opposite effect of decreasing blood flow.  As soon as the body senses the skin has been punctured it seeks to stop the blood flow with clotting factors.  Wait just a second before gently milking or squeezing and you will find that the fingertip will produce blood more easily.
       
    • Saturate the test strip area with blood.  If you do not, you will get an error message and have to start all over again. Sometimes, if the finger is wet or contaminated you will also get an error message.
       
    • Read the meter and take any corresponding action necessary.     

    Important Tips for Accuracy

    • Make sure fingertips (or alternate site) are clean and dry.
       
    • Make sure you supply enough blood to the test strip area.
       
    • Make sure the meter is calibrated (some meters do not require calibration) whenever you use a new vial of test strips.
       
    • Make sure your meter settings are correctly set for ml/dL or mol.  Whatever setting you use make sure you know which setting the meter is on otherwise you will misinterpret the results.
       
    • If you use alternate sites be aware that this is NOT the most accurate blood glucose reading.  The body is dynamic and there is a delay in blood glucose between fingertip and forearm.  Forearms are not a reliable test site (nor other areas including toes) which will register blood glucose higher than fingertips.  If your alternative site reading is low, repeat on the finger tips.  If your alternate site is normal or high but you still feel like you could be low, or have any of the symptoms of low blood glucose, repeat the test on the finger tip!
       
    • Take good care of your meter and test strips.  Do not expose them to heat, moisture or direct sunlight.  This can damage the equipment and produce false readings. If you ever suspect that your meter is not performing properly throw it away and get a new one!

    Always have a backup meter handy, and never, ever go anywhere without a meter, plenty of test strips, lancing supplies, fast-acting sugars, medical identification bracelet and information card for your wallet or purse, and, if you are on insulin, always carry a glucagon kit.    

    Special Care Tips For Children

    Remember that most children are fairly resilient; they will adapt to their diabetes care program probably a lot faster than you will.  Letting a child return to normal activities after diagnosis is scary for parents, but crucial for children's mental health. Here are some tips to help ease the transition from "everything's rosy" to dealing with a serious, and chronic illness:

    • Children need reassurance from you.  Needles are no fun and once diagnosed, will be a fact of life for a child with diabetes.  Practice on yourself to see what works best and produces the least amount of discomfort.  If nothing else, it may help you better understand what you child has to go through.
       
    • If your child resists glucose checks (or shots) don't yell or fight.  This will only increase their tension (and your own) and you will end up chasing your child around the house and having to pin them to the floor to test them.  Calmly explain that it needs to be done and when it is over they will get a nice cuddle or story.  Offer rewards that are emotionally supportive (like time, hugs, kisses, and tickles) rather than toys, money, or food.
       
    • When your child shows anger or sadness over diabetes and what the care entails, agree with them and validate their feelings.  "Yeah, diabetes stinks," goes a long way with children.  You can then offer coping skills and positive slants such as reminding them you are in this together.
       
    • Never belittle your child if they say finger sticks or shots hurt -- they can and do.  Dismissing your child's anxieties will not help.  Instead, ask them for their input as to how to do it better.  Apologize, "I'm sorry this hurts.  Can you help me by telling me how we can do this to make it more comfortable for you?"
       
    • Children, even as young as age 3 are perfectly capable of performing their own finger sticks and even injections with adult supervision.  As soon as they are interested in taking control of glucose checks or shots (Elizabeth has been giving her own boluses via her pump since age 5 -- I double checked that she enter the right amount -- and finger sticks since age 4.)
    • Give your child a comfort buddy like a stuffed animal or soft doll.  Let them have their own lancing device (without a lancet) and syringe with the needle removed to care for their buddy while you care for your child.  Many online stores sell diabetes buddies and even dolls with mini insulin pumps for play.  Many local JDRF chapters also give out comfort buddies to children.

    If your child, you, or other family members are having trouble dealing with diabetes, seek counseling or therapy from a mental health professional because a chronic illness affects the entire family.


    Section 2

    How They Work and Various Meter Features

    In the United States, blood glucose is measured in mg/dL (milligrams per deciliter).  In most other countries, blood glucose is measured in mmol/l.  Many meters can be set for either measurement so it is very important that you always make sure your meter is set to the measurement you are familiar with.

    Blood glucose meters measure how much glucose is in a given blood sample.  Where the sample comes from (fingers, toes, forearms, ear lobes) will affect test results.  Although alternative site testing is enticing (claiming to be less painful) I personally do not feel it is accurate enough for use on young children that cannot sense their own symptoms of hypoglycemia.  Readings from forearm (or toe) blood lag behind fingertip blood and cannot accurately reflect rapidly changing glucose levels in the rest of the body.  This means that a forearm sample could come back higher than is actually true and a person could really be suffering from hypoglycemia (low blood glucose) and need treatment.

    A test strip is placed inside a blood glucose meter (you can ONLY use test strips designed for your particular meter). A drop of blood is then placed on the strip.  Blood reacts with chemicals in the test strip causing a small electronic pulse to be sent into the meter which then calculates the level of glucose in the blood sample and shows the result in a digital display.

    Different makes of meters offer a variety of functions and data management capabilities to match individual testing needs. Newer models of meters feature one-step sampling and readout. The chemically-treated strip is placed in the device and a drop of blood is placed on the test strip which acts like a straw drawing the blood sample into the strip. and the meter then gives a reading.

    Newer meters offer on screen averages for week or months at a time, can hold hundreds of previous test results with time and date, and may even have graphing capability. The new generation of meters may also have upload features so that a person or doctor can upload meter readings directly from the meter and into a computer for analysis and review. Some meters allow entry of additional data throughout the day, such as insulin dose, amount of carbohydrates eaten, stress, illness, or exercise data.   Not all meters have these feature so be sure to talk with your doctor about what features are available and suit your needs best.

    Alternative Testing Sites

    Some meters offer alternate site testing, which allows a consumer to test on sites other than the fingertips, which can become sore and callused over time.  However, alternate site testing is not as accurate as finger pricks.  If your reading is low from an alternate test site (i.e., forearm), or you feel like you may be low, you still have to repeat the test on a fingertip.  (I personally find finger sticks not only more accurate, but also less painful when done properly.  

    The main drawback of alternative site testing is that they are not consistently reliable.    A person may test higher on the forearm than if they had tested on their fingers.  This can be a real problem if a person (especially child) is already on the low side.  A false higher reading may prompt a parent to give a correction bolus when in fact, the child is already, or heading into, a state of hypoglycemia (low blood glucose) 

     For now, finger tip testing is still more reliable than alternate site testing.    

    Why Should I Test My Blood Glucose?

    The glucose meter is a key element of home blood glucose monitoring (HBGM, also called "self glucose monitoring") by people with diabetes mellitus and other disorders that require blood glucose monitoring. Since approximately 1980, a primary goal of the management of type 1 diabetes has been the achievement of closer-to-normal levels of glucose in the blood for as much of the time as possible, guided by HBGM several times a day. This has greatly increased the trouble and time spent in the daily care of this disease but has also reduced rates of long-term complications and improved the management of short-term complications such as hypoglycemia.  It is estimated that approximately 85% of all diabetics do not adequately keep their blood glucose levels at, or near, their target ranges.  This may be one reason for the high rate of associated diabetes complications. The best way to manage your blood glucose levels is simple: test regularly, and often.  You cannot correct highs and lows if you don't know about them.

    Glucose monitoring is also an important tool for helping your doctor determine your best care plan approach.  Readings can help determine what your basal (background) insulin should be, as well as your insulin-to-carb ration, correction factor, and how your blood glucose levels are faring during the night.

    Meter Use For Hypoglycemia

    Although the apparent value of immediate measurement of blood glucose might seem to be higher for hypoglycemia than hyperglycemia, meters have been less useful. The primary problems are precision and ratio of false positive and negative results. An imprecision of ±15% is less of a problem for high glucose levels than low. There is little difference in the management of a glucose of 200 mg/dl compared with 260 (i.e., a "true" glucose of 230±15%), but the difference between 70 mg/dl and 55 (i.e., 67±15%) represents a more unsatisfactory uncertainty. The imprecision is compounded by the relative likelihood of false positives and negatives in populations of people with diabetes and those without diabetes. People with type 1 diabetes usually have glucose levels above normal, often ranging from 40 to 500 mg/dl, and when a meter reading of 50 or 70 is accompanied by their usual hypoglycemic symptoms, there is little uncertainty about the reading representing a "true positive" and little harm done if it is a "false positive."

    In contrast, people who do not have diabetes but periodically have hypoglycemic symptoms, will have a much higher rate of false positives to true, and a meter is not accurate enough to base a diagnosis of hypoglycemia upon. Hypoglycemia (unrelated to diabetes) needs to be diagnosed by a medical professional.

    A meter can occasionally be useful in the monitoring of severe types of hypoglycemia (e.g., congenital hyperinsulinemia), to ensure that the average glucose when fasting remain above 70 mg/dl.     

    When Should I Test My Blood Glucose?

    Your doctor will help you decide when to test and how often.  However, the more often you test the better your chances of catching lows and avoiding highs; both important factors in reducing your risk of long-term complications of diabetes.

    Generally, most physicians will advise that you test:

    • Morning fasting blood glucose, before breakfast
    • Two hours post-prandial (after eating all your meals)
    • At lunch time
    • At dinner time
    • Before bedtime
    • Once, or more during the night (especially if you wake with symptoms of the Dawn Effect (Phenomenon) or Simogyi Effect.
    • Any time you have any of the symptoms of hypoglycemia (low) blood glucose, of hyperglycemia (high blood glucose).
    • Your doctor may also advise you to test more often during illness, or stressful events.
    • Before, during, and after (excessive) exercise.
    • It is also a good idea to test more frequently when driving for long periods because it is important to keep your glucose above 70 mg/dL while driving.
    • Anytime there is a change in your care plan (increase or decrease in insulin, or when it is administered, or change in insulin, or addition of medications) you will need to test more often to see how your body reacts.
    • You will also need to test more frequently if you are on an insulin pump, especially at first.  But the benefits of pumping far outweigh the inconvenience of extra finger sticks!

    Also, you need to RECHECK blood glucose levels anytime you have suffered a hypoglycemia episode (70 mg/dL or lower) that required treatment.  Keep rechecking blood glucose until your levels have stabilized.     

    Meter Accuracy

    Accuracy of glucose meters is a common topic of concern. Nearly all of the meters have similar accuracy (±10-15%) when used correctly. However, a variety of factors can affect the accuracy of a test including calibration of meter, ambient temperature, pressure use to wipe off strip, size of blood sample, high levels of certain drugs in blood, hematocrit (blood iron levels), dirt on meter, aging of test strips, and of course, wet fingers or fingers that are dirty or contaminated with food. Models vary in their susceptibility to these factors, and in their ability to prevent or warn of inaccurate results with error messages.