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What Can Cause False High Blood Sugar Readings

Why Is It Important For A Blood Glucose Meter To Be Accurate

Not Eating Sugar Yet High Blood Sugar Levels?

Blood glucose meter accuracy is important for several reasons:

  • Improved reliability in your data and trust in your current diabetes management plan.
  • Helps you understand and/or anticipate potential lab results when going for your A1c checkup.
  • Lets you know what impacts your blood sugar:
  • Did that glass of wine last night have a significant impact?
  • Did you experience a spike or drop in blood sugar after that amazing Zumba class?
  • Is there a connection between your stress and blood sugar?
  • Accurate meters are able to detect episodes of hypo- or hyperglycemia.
  • Can help with decision-making surrounding medication dosages.
  • The Bodys Response To Illness

    Illness produces a stress response in the body and increases levels of cortisol, adrenaline, growth hormone, and glucagon. When the body responds to the stress of illness, insulin levels fall and the body releases more glucose to ensure that it is prepared with sufficient energy to react. If blood sugar levels are too low, the body wont have enough energy to react to the stress response.

    As stress hormones increase, the body becomes less responsive to insulin, resulting in excess glucose in the blood stream. When the blood is loaded with glucose, white blood cells are unable to reach the intruding bacteria or virus. A slow immune response keeps the body from recovering efficiently and may lead to further complications.

    Thyroid And High Blood Sugar

    High blood sugar, or hyperglycemia, is a common health concern affecting millions of people. There are two main types of hyperglycemia:

    • Fasting hyperglycemia blood sugar levels higher than 130 mg/dl and it usually occurs when a person doesnt eat or drink for more than eight hours
    • Postprandial hyperglycemia blood sugar levels higher than 180 mg/dl about two hours after the meal. That being said, nondiabetic individuals rarely have blood sugar levels higher than 140 mg/dl after they eat

    The relationship between high blood sugar and thyroid functioning can be discussed from different angles including insulin resistance, metabolic syndrome, and diabetes.

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    How To Prevent Hyperglycaemia

    There are simple ways to reduce your risk of severe or prolonged hyperglycaemia:

    • Be careful what you eat be particularly aware of how snacking and eating sugary foods or carbohydrates can affect your blood sugar level.
    • Stick to your treatment plan remember to take your insulin or other diabetes medications as recommended by your care team.
    • Be as active as possible getting regular exercise can help stop your blood sugar level rising, but you should check with your doctor first if you’re taking diabetes medication, as some medicines can lead to hypoglycaemia if you exercise too much
    • Take extra care when you’re ill your care team can provide you with some “sick day rules” that outline what you can do to keep your blood sugar level under control during an illness.
    • Monitor your blood sugar level your care team may suggest using a device to check your level at home, so you can spot an increase early and take steps to stop it.

    Testing Technique And Site

    What Can Cause False High Blood Sugar Readings ...

    Make sure youre following the directions of your meter. Traditionally, fingertips are the primary place to test your blood sugar. Alternative testing sites such as on the palm, upper arm, forearm, thigh, and calf are used, typically in clinical settings, instead of fingers due to the many nerve endings on fingers, including the pain from testing and the resulting calloused fingers. But, it isnt advised to use an alternate site unless you have a device thats designed for it. However, using an alternate site may not always produce accurate results, especially if your blood sugar is rising or falling fast. Research shows that glucose readings differ depending on if you get your blood sample from the capillaries in your fingers or another part of your body.

    Another note about the technique make sure you have enough blood in your test strip. Having too little blood will cause an error or false reading. You can adjust the settings on your lancet to make sure youre drawing enough blood. Finally, make sure youre fully inserting the test strip into your meter.

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    Common Blood Sugar Testing Mistakes

    Good blood sugar control requires good blood sugar testing. Though that can be challenging, avoiding common mistakes can help you get the most consistent results.


    Blood glucose testing is an important part of managing type 2 diabetes and staying on top of blood sugar control. Testing regularly shows you how food, exercise, and other factors affect your blood sugar. provides valuable information regarding how blood glucose is doing at a moment in time, says certified diabetes educator Alison Massey, MS, RD, LDN, CDE, director of diabetes education at Mercy Medical Center in Baltimore. It gives people an idea of whether blood sugar is in a healthy or unhealthy place.

    But blood sugar testing isnt always easy and an array of mistakes can affect your results. In fact, it can be hard to fully understand the guidelines on managing blood sugar testing, according to a study published in the May 2015 issue of the Journal of Diabetes and Metabolic Disorders.

    The good news: A little practice can help you get blood sugar testing right. Start by learning how to avoid these common mistakes.

    Mistake #1: Buying a blood sugar meter that doesnt fit your daily life

    Mistake #2: Selecting a device your insurance wont cover

    Mistake #3: Setting up the incorrect time and day on your meter

    Mistake #4: Testing at the wrong time

    Mistake #5: Not getting into a routine

    Mistake #6: Not cleaning your hands before checking your blood sugar

    How A Cold Or The Flu Affects Blood Sugar Levels

    Individuals with diabetes are more vulnerable to health complications if they come down with the flu or a cold. According to the Center for Disease Control and Prevention, individuals diagnosed with diabetes are 3 times more likely to be hospitalized for complications due to the flu than those who dont have diabetes.

    For this reason, diabetes patients should take extra precautions to protect themselves from colds or the flu. Any kind of physiological stress on the body will raise blood glucose levels and may make it more difficult to manage diabetes.

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    Anemia Can Cause False A1c Reading

    Whoa! This was news to me. Just found this little gem on a wonderful site called Since Im chronically and horribly anemic from heavy menstrual periods, this was of great interest to me. After reading this, Ill definitely be having a discussion with my doctor on my next visit.

    Q: Can the Hgb A1c Blood Tests give false reading?

    A: The A1c test can read lower than it really is if you are anemic . The more anemic you are, the more the Hgb A1c blood test is falsely lowered.

    If you frequently have blood sugars that meet the definition of hypoglycemia, then your A1c blood test could be in target even though you might have high blood sugars often. The highs and lows seem to average out. Dont fool yourself into believing all is well. The highs can still do damage despite all the low sugars .

    If you have great blood sugar readings at home but your Hgb A1c blood test is high, your meter might be inaccurate. Check for diabetes test strips accuracy problems.

    If your glycated hemoglobin is high but your before meal tests are in target, then please consider doing post prandial or after meal blood sugar tests. These too can affect your chance of getting complications.

    The Hgb A1c blood test can be higher than it really is if you have unusual hemoglobin. For example, a very small population of people have some fetal hemoglobin which can falsely elevate the A1c reading.

    What Can Make My Blood Sugar Rise

    10 High Blood Sugar Warning Signs

    Hyperglycemia is the technical term for high blood sugar . It happens when the body has too little insulin or when the body can’t use insulin properly. Here are a few of the causes:

    • Too much food, like a meal or snack with more carbohydrates than usual
    • Dehydration
    • Not enoughinsulinor oral diabetes medications
    • Side effects from other medications, such as steroids or anti-psychotic medications
    • Illness, stress, menstrual periods or short or long-term pain

    The good news is, there are things you can do to avoid highsand to treat them when you get them.

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    Other Causes Of False Blood Pressure Readings

    The following are things you may be doing that will raise or lower your blood pressure temporarily. At the exact moment of measurement, your blood pressure will probably be different than what it is the rest of the day. This will give you a false indication of your blood pressure, even though it was accurate at the time of measurement .

    • Dont exercise, drink caffeine or smoke within 30 minutes of taking your blood pressure.
    • If you feel like you have to urinate or do a number two, go to the bathroom prior to measuring your BP. Anything that may stress your body or mind may raise your pressure.
    • Dont talk while taking your blood pressure. I knew someone who would use their home monitor while talking on the phone. This can definitely change your BP, especially if the conversation is stressful.
    • Make sure the 5 minutes prior to taking your measurement are restful and quiet.
    • This is more of a tip than a mistake. At the initial Bp measurement, take readings in both arms. Its normal to have a slight difference between the two arms. The arm with the higher measurement should be used for all subsequent readings .

    If you found this Blood Pressure topic interesting check out these related blood pressure articles also found in this same website:

    What Causes Blood Sugar To Rise Without Eating

    For the most part, food as you gathered from above, is the main driver for rises in blood sugar. However, life as you know is never a straight line.

    There are other factors that can cause blood sugar to rise without eating. Some of that has to do with inter-play of hormones.

    Stress hormones like cortisol, catecholamines , mobilize glucose from the stored glucose in the liver. Glycogen is the stored form of glucose in the liver.

    These hormones cause a rise in blood sugar without eating both in diabetics and non-diabetics. Any thing that causes stress to your body will cause your blood sugar to rise.

    Prescription and some over-the-counter medications like nasal decongestants can also cause your blood sugar to rise without eating.

    Below are some of the causes of high blood sugar without eating:

    • Steroid medication
    • Diuretics pills that make you pee
    • Nasal decongestants containing phenylephrine or pseoudoephedrine
    • Poor sleep

    As you tell from the above list, yes, stress can cause high blood sugar in non-diabetics. Stress from whatever origin has the potential to increase cortisol levels in the blood.

    And as I explained earlier anything that causes liver cells to mobilize their glycogen stores unnecessarily will raise your blood sugar. Stress will do just that.

    Should non-diabetics check blood sugar?

    And Guess what

    So, yes, my advice is that non-diabetics can test for blood sugar, if you are looking for some guidance on the matter.

    Suggested further reading:

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    Test Strip Quality And Compatibility

    This is a major one. If you can, use the test strips of the same brand as your meter. Some third-party products are compatible with branded meters, but not always. Using an incompatible test strip can cause inaccurate or error readings different manufacturers have their own processes for developing their test strips. Test strips also come with expiration dates dont use strips beyond the expiration date. Lastly, beware of using test strips that are unauthorized for sale or that were previously owned.

    Blood Glucose Meter Calibration Quality And Coding


    In order to trust the data your meter is providing you, make sure youre getting a quality meter. We discuss this more below, but manufacturers must meet certain standards to be considered accurate. If youre unsure about the quality of the meter, check for the latest updates and versions by the maker.

    When you first set up your meter, follow the directions included with it. The calibration process can vary per manufacturer and meter. Finally, your meter will need to match a calibration code with the number on the test strip vial. Some meters are the exception to this. For example, with an Accu-Chek meter, theres no need to code it, so you have fewer steps in glucose testing.

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    Food And Cholesterol Levels

    Cholesterol is a waxy, fat-like substance produced in the liver, according to the American Heart Association. Though you may think of cholesterol as “bad,” the body actually needs cholesterol to function properly.

    Cholesterol can also be found in foods such as meat, dairy, eggs and baked goods. However, the relationship between food and blood cholesterol is more complicated than previously believed.

    Until recently, it was though that eating lots of cholesterol-rich foods played a significant role in causing high blood cholesterol. But a major 2015 report by the USDA Dietary Guidelines Advisory Committee found that cholesterol from food called dietary cholesterol has a much smaller effect on a person’s blood cholesterol.

    Read more:The Truth About How Your Diet Affects Your Cholesterol

    Instead, a diet high in fats and carbohydrates has a much greater effect on blood cholesterol, according to the Harvard T. H. Chan School of Public Health. But you should note that many cholesterol-rich foods are also high in saturated fats. This is why Dr. Eckel says it’s still best to limit or avoid meat, dairy and baked goods.

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    Food Taken At The Previous Night

    A diabetic patient has to follow a strict diet. The number of carbohydrates and sugar cannot exceed the doctors prescribed amount.

    A blood sugar spike in the morning can occur if the patient takes more food than the medications can handle. Try to remember the last meal that you took before going to bed.

    You have most likely taken more food than what your endocrinologist advised you to have.

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    Why The Test Is Performed

    Your doctor may order this test if you have signs of diabetes . More than likely, the doctor will order a fasting blood sugar test.

    The blood glucose test is also used to monitor people who already have diabetes.

    The test may also be done if you have:

    • An increase in how often you need to urinate
    • Recently gained a lot of weight
    • Blurred vision


    This test may also be used to screen a person for diabetes.

    High blood sugar and diabetes may not cause symptoms in the early stages. A fasting blood sugar test is almost always done to screen for diabetes.

    If you are over age 45, you should be tested every 3 years.

    If you’re overweight and have any of the risk factors below, ask your health care provider about getting tested at an earlier age and more often:

    • High blood sugar level on a previous test
    • Blood pressure of 140/90 mm Hg or higher, or unhealthy cholesterol levels
    • History of heart disease
    • Member of a high-risk ethnic group
    • Woman who has been diagnosed with gestational diabetes
    • Polycystic ovary disease
    • Close relative with diabetes
    • Not physically active

    Children age 10 and older who are overweight and have at least two of the risk factors listed above should be tested for type 2 diabetes every 3 years, even if they have no symptoms.

    What Can Make My Blood Sugar Fall

    8 Signs Of High Blood Sugar Levels

    Hypoglycemia is the technical term for low blood sugar . Its when your blood sugar levels have fallen low enough that you need to take action to bring them back to your target range. Here are a few of the causes:

    • Not enough food, like a meal or snack with fewer carbohydrates than usual, or missing a meal or snack
    • Alcohol, especially on an empty stomach
    • Too much insulin or oral diabetes medications
    • Side effects from other medications
    • More physical activity or exercise than usual

    Dont worry: There are things you can do to avoid lows. Be sure to learn the symptoms, and how to treat them when you get them.

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    Be Aware Of False Glucose Results With Point

    Point-of-care blood glucose monitoring systems are known to provide an accurate, timely, and cost-effective means for determining blood glucose levels in diabetic patients. In fact, these devices have become a mainstay for blood glucose monitoring in both hospitals and outpatient settings. In many cases, this has allowed patients to achieve better glycemic control and avert the negative health outcomes associated with hypoglycemia or hyperglycemia. However, patients and practitioners may not know that the administration of certain substances can result in erroneously high values when using glucose meters. One situation was recently reported.

    Regulatory agencies in Australia, Canada, and the United Kingdom have received similar reports describing this substance-device interaction. These agencies found that maltose interacts with numerous test strips, including those used with certain Accu-Chek and Ascensia systems, as well as Freestyle test strips . This interaction has resulted in false readings of hyperglycemia and unnecessary insulin administration, sometimes leading to injury and death. Additionally, falsely elevated glucose readings could mask true hypoglycemia, which also could result in fatal consequences if left untreated.

    Consider the following suggestions to reduce the risk of reliance upon potentially false glucose meter readings from point-of-care systems.

    /98 Factors That Can Give An Inaccurate Blood Sugar Reading

    As per the International Diabetes Foundation, 42.5 crore people suffer from diabetes globally and this number is expected to increase to 62.9 crores by 2045.

    Talking about India, studies have shown that prevalence of diabetes in urban areas has increased from 2 per cent in 1970 to 25 per cent in 2015 and in rural areas from 1 per cent to 14-16 per cent, respectively.

    The data is shocking and alarming. To keep our blood sugar levels in check, we rely on glucose testing. But the thing is, these readings might be inaccurate sometimes. Though with the advancement in technology, modern meters have made inaccurate readings less common. But it still can happen and here’s why.

    Here are eight reasons why your meter can show inaccurate reading and what you can do about it.

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