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A1c Correlation To Blood Glucose

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How Often Should I Get My A1c Checked

A1C Levels

For people with type 2 diabetes, If your A1C is high, your care team may ask you to come back every three months until it falls back into range.

If your management seems to be going well, your doctor may ask you get checked twice per year.

If youre taking insulin, or oral medication, you may continue seeing your care team every three months for adjustments and an A1C test.

How Should You Assess Glycemic Control If The Hemoglobin A1c Is Inaccurate Or Uninterpretable

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For adult outpatients with type 2 diabetes mellitus, hemoglobin A1c is the standard test used to gauge overall glycemic control during the previous 2 to 3 months and to titrate antidiabetic medications. But hemoglobin A1c does not provide an accurate assessment of frequency or severity of hypoglycemic events. Also, in some instances it may not truly represent glucose control, reflecting an average of high and low blood sugar values, or may not be reportable because of abnormal hemoglobin.

In these situations, an alternative test can be used along with capillary blood glucose testing, which remains the most reliable method of assessing glucose control in the short term. If an alternative test is used, it is important to clearly document it in the chart to reduce confusion, and also to educate the patient to better understand the disease-monitoring process.

Continuous Glucose Monitoring Systems

Continuous glucose monitoring systems measure glucose concentrations in the interstitial fluid. Two types of devices are available. The real time CGM provides information directly to the user by displaying moment-tomoment absolute glucose levels and trending arrows, and by providing alarm notifications in the event that the glucose level is above or below a preset limit. A blinded CGM captures, but does not display, the glucose readings, which are then downloaded onto a computer for viewing and retrospective analysis by the health-care provider .

CGM technology incorporates a subcutaneously inserted sensor, an attached transmitter and, in the case of real-time CGM, a display unit . In professional CGM, the transmitter captures and retains the data. In Canada, 2 real-time CGM and 2 professional CGM are available. Real-time CGM has been consistently shown to reduce A1C in both adults and children with type 1 diabetes with and without CSII, and to reduce A1C in adults with type 2 diabetes . Real-time CGM also has been shown to reduce the time spent in hypoglycemia . Professional CGM has been shown to reduce A1C in adults with type 2 diabetes and in pregnant women with type 1 or type 2 diabetes .

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What Exactly Is Blood Glucose

The simple term blood glucose is surprisingly complex. First, blood glucose can be highly variable, increasing rapidly after a carbohydrate meal and then falling to the relatively steady fasting state. The fasting state is itself a dynamic state, where the removal of glucose from the blood is at first balanced by glycogen breakdown and then supported by gluconeogenesis. Second, as Gambino has emphasized, our estimation of blood glucose is problematic, and estimates can differ by up to 14% from laboratory to laboratory, reflecting a suboptimal state of the art when it comes to glucose measurement.6 This could be improved by calibration and preservation of stored samples to inhibit in vitro glycolysis. However, when it comes to the measuring of glucose levels in diabetes patients, we should always clearly define the matrix we are referring to.

Whole Blood Versus Plasma

How do blood sugar levels correlate to a1c?

Despite whole blood glucose being the most common measurement in medicine worldwide, we can begin this discussion with the observation that there is no internationally recognized reference method for the measurement of blood glucose.7 This difficulty stems from the composition of blood, being predominantly a mixture of plasma and the red blood cell hematocrit. Plasma is largely water , the rest being accounted for by protein and lipids. Red blood cells are also largely water , and water-soluble glucose can diffuse freely into that compartment. The concentration of glucose in the red cell is 0.763 of the concentration of glucose in plasma . The higher the hematocrit, the more the overall blood glucose concentration will reflect the red cells and vice versa. The difficulty in standardizing whole blood glucose measurements relies on this fact, and not surprisingly, the use of whole blood glucose standards improves the agreement of whole blood meters8 as does the simultaneous measurement of hematocrit.9

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Use This Chart To View A1c Values And Comparable Blood Glucose Values:

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A note of caution: the A1c measurement is not always accurate. For example, if someone has certain type of hemoglobin mutations , is severely anemic , or is being treated blood transfusions or medications to increase the production of new red blood cells, the A1c test may not be accurate.

If your finger-stick blood tests give an average blood sugar that is much higher or lower than your A1c test, ask your doctor if the A1c is the right test for you. An alternative test to the A1c is a fructosamine test. Unfortunately, the fructosamine test and the A1c are not interchangeable because they are measuring different things. The fructosamine test reflects the average blood sugars only over a 2-3 week period.

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Hemoglobin A1c Correlations Against Multiple Glucose Values

Ozmen and colleagues36 showed that, while any single glucose value correlates with HbA1c, better correlations are achieved by averaging the glucose values of an individual. Bonora and associates37 found that preprandial glucose levels were slightly better than postprandial glucose levels when correlated with HbA1c however, they also concluded that averaging these values gave the best correlation.

In 1982, Svendson and coworkers38 reported that the average glucose levels derived from approximately 2 to 300 measurements in each of 18 type 1 diabetes patients correlated almost perfectly with glycosylated hemoglobin.

While most similar studies have been performed in type 1 diabetes patients, Makris and colleagues39 have shown that average glucometer glucose values in 140 type 2 diabetes patients also correlates with HbA1c over the preceding 12 weeks. They calculated their averages from a minimum of 72 individual measurements taken in the preceding month. The correlation was similarly exceptionally strong with a regression equation of mean blood glucose = 34.74 × HbA1c – 79.21. The strength of their correlation, however, could also be contributed to by the greater stability of glucose levels in type 2 compared to type 1 diabetes patients.

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Why Do People With Diabetes Have An A1c Test

People with diabetes will have an A1C test done in order for their doctor to understand how treatment is working.

A1Cs are not a grade. Rather, they are a way to make sure treatments like, insulin, oral medication, diet and exercise are working as intended.

Your doctor may adjust your treatment based on your A1C. Using the calculator above, however, is not a meaningful way to make treatment decisions on your own.

See your doctor if you believe you need a change in your treatment.

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Hgb A1c Chart For Diabetes

HbA1c Test and What HbA1c Normal Range Means

Contains the levels of A1c that considered high for people suffering from DM patients whose treatment based on metformin or insulin.Any reading of A1c is greater than 6.5 tells you have got DM according to ADA guidelines,although for people who are already have DM and taking medications the levels from 7 to 8 is the target value they should shoot for.However persons with type 1 DM and are on insulin especially children may show A1c levels over 10,and they must fight to lower their Hgb a1c levels to theee goal targets.Two consecutive tests show high A1c levels confirm the diagnosis of DM and means that the person has diabetes millitus type 2 or type 1.For a person on metformin and A1c 7% it means he achieved the target value for type 2 diabetes mellitus.However, for type 1 diabetes millitus and persons taking insulin to control DM the A1c 8.0 is mild as all his results may hit the A1c 12%.

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How Does A1c Affect Blood Glucose Testing

If your A1C level is off target, you may need to test your blood sugar more frequently to determine when your levels are higher and if there is a pattern that can help your healthcare providers determine a treatment plan.

Of course, if your A1C levels are fine, you may not need to test as frequently. For more on how often to check your blood glucose levels go to this article.

Checking both your A1C and blood sugar levels regularly is an important way to stay on top of managing your diabetes.

What Can You Do To Improve Your A1c Levels

People often wonder how long it will take to improve their A1C number. By following your diabetes self-care plan, you can improve your A1C by your next three-month check. Your A1C may continue to go down at each visit if you continue to partner with your healthcare provider and follow the tips above.

Its not helpful to test your A1C more frequently than every three months, and more frequent testing is not always covered by insurance. If you feel like you have followed your healthcare providers recommendations but your A1C level is high, dont take it personally. Again, there are many factors that make diabetes management difficult, and if you continue to work on it, your number will come down.

In summary, the A1C test gives you a picture of your overall glucose levels. There is no bad or good number, just information that helps you and your healthcare provider understand how well your diabetes management plan is working.

Using an A1C calculator can give you an idea of how your A1C translates into an EAG number that you can recognize, using the same unit of measurement as shown on a blood glucose meter. However, remember that A1C goals can be different for each person based on age, treatment goals, access to diabetes supplies, and other health issues present, so dont be afraid to talk with your healthcare professional about setting your unique goals to lead to better diabetes management.

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Why Use An A1c Calculator

Self-monitoring tools such as traditional blood glucose meters , continuous blood glucose monitors , and automatic blood glucose monitors report blood sugar in mg/dL or mmol/L, not a percentage. As a result, it can be difficult to understand the relationship between your daily blood sugar levels and your A1c results. An A1c calculator may give you a sense of how your average blood glucose matches up with the individual readings you take.

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Benefits Of Lowering Your A1c Test Result

Pin on Diabetes. Jugos

Keeping your A1C test results low can significantly reduce the risk of long-term diabetes complications such as nerve problems, damage to your eyes, kidney disease and heart problems.3

1American Diabetes Association. Standards of medical care in diabetes2017 . Diabetes Care. 2017 40: S1-S135. Available at: . Accessed July 28, 2017.

2Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008 31: 1473-1478. Available at . Accessed July 28, 2017.

3American Diabetes Association. A1C and eAG. Available at: . Accessed July 28, 2017.

4Tylee TS, Trence DL. Glycemic variability: looking beyond the A1C. Diabetes Spectrum. 2012 24: 149-153. Available at . Accessed July 28, 2017.

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What Can I Learn From Converting My Hba1c To Average Blood Glucose Level

Converting your lab test HbA1c to average blood glucose level can be useful to compare your own average blood glucose results.

If, for example, your own average blood glucose results are lower than the average provided by the calculator, this suggests you may not be testing during periods of the day when your blood glucose levels are higher, which could include after meals.

You may therefore wish to carry out more blood glucose testing at different times of day to see if you are experiencing high results that you may not otherwise be aware of.

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Interstitial Glucose Versus Arterial Glucose

Interstitial glucose measurement refers to subcutaneous glucose sensors that are not placed within blood vessels. Although these sensors are not measuring blood glucose levels directly, interstitial glucose levels generally have good agreement with arterial levels.27 It is commonly believed that interstitial glucose levels lag approximately 15 min behind arterial levels due to the time required for glucose to diffuse into the interstitial space. However, studies suggest that this lag may be due partly to amperometric sensor response times and even more largely due to digital averaging by the devices .28 In any event, the interstitial devices are usually calibrated against whole blood glucose capillary measurements, which are in turn standardized against plasma glucose equivalents. This ultimately results in interstitial glucose levels that generally correlate with blood glucose values measured in the laboratory.24

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How Accurate Are The Results

The calculator looks to provide an estimate of what your HbA1c value may be based upon your average blood glucose results and vice versa. Its important to note that HbA1c and blood glucose tests measure different things.

Blood glucose tests measure the concentration of glucose molecules in the blood at a single point in time.

The HbA1c test measures the proportion of haemoglobin molecules in the blood that have become chemically bonded with glucose over a period of up to 3 months.

However, the calculator serves as a useful guide which can give you a close indication of what your HbA1c result might be based on your blood glucose results?

When The Blood Glucose And The Hba1c Dont Match: Turning Uncertainty Into Opportunity

What is A1C Test? Is it an Accurate Blood Test? Dr.Berg

Diabetes Care

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  • Robert M. Cohen, Christopher J. Lindsell When the Blood Glucose and the HbA1c Dont Match: Turning Uncertainty Into Opportunity. Diabetes Care 1 December 2012 35 : 24212423.

    Acentral principle in science and medicine is that the more independent pieces of evidence there are that agree, the more convincing it is that a hypothesisor diagnosisis valid. The opposite is also true: discordant information leads to uncertainty. Unfortunately, it is not uncommon for clinicians caring for people with diabetes to encounter individuals in whom HbA1c and blood glucose simply do not match. Sometimes, there is an obvious explanation such as hemolytic anemia. But when it occurs in people with reliable blood glucose records and ostensibly normal peripheral blood and reticulocyte counts, without evidence of hemoglobinopathy, hemolytic disorder, blood loss/transfusion, or nutritional deficiency such as iron, folate, or vitamin B12, we are left with the questions of how the discordant information should be treated and what it means for patient care.

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    Type 2 Diabetes Not Treated With Insulin

    For people with type 2 diabetes treated with healthy behaviour interventions, with or without noninsulin antihyperglycemic agents, the effectiveness and frequency of monitoring BG in improving glycemic control is less clear . A series of recent meta-analyses, all using different methodologies and inclusion criteria, have generally shown a small benefit to reducing A1C in those individuals performing SMBG compared to those who did not . The magnitude of the benefit is small, with absolute A1C reductions ranging from 0.2% to 0.5%. These analyses demonstrated greater A1C reductions in those performing SMBG when the baseline A1C was > 8% . SMBG has been demonstrated to be most effective in persons with type 2 diabetes within the first 6 months after diagnosis . Also of significance, there is no evidence that SMBG affects one’s satisfaction, general well-being or general health-related quality of life .

    Correlation Between Continuous Glucose Monitoring Glucose And Hemoglobin A1c

    Sharp and Rainbow57 found that the mean sensor glucose value obtained with the Continuous Glucose Monitoring System was highly correlated with the HbA1c at the time of insertion . It could be surprising if the correlation was much better, as they were trying to predict the average glucose values of the next 2 to 6 days using the HbA1c that reflects the glucose values of the previous 120 days.

    Salardi and colleagues58 made similar observations correlating the area under the glucose curve derived from CGM with HbA1c taken prior to CGM and obtained r2 values between 0.07 and 0.30, which generally improved as the average glucose levels increased. They concluded that, to improve metabolic control, it is necessary to lower the whole mean 24 h glycemia.

    Salardi and associates58summarized the superiority of CGMS in correlating with HbA1c by concluding that, According to our data, it seems that the whole daily glycemia, and not a single glucose value, is an important determinant in the overall glycemic control, as measured by HbA1c.

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    What If My Hba1c Is Normal But My Glucose Is Above Optimized

    Sleep deprivation

    Theres evidence that poor sleep patterns impair glucose metabolism. People on restricted sleep demonstrate worsened insulin response to food, resulting in higher blood glucose spikes. In one study, sleep-deprived people had higher glucose and insulin levels after consuming breakfast compared to those who slept a healthy eight hours. Other studies confirm this findinginsulin resistance is more common in people deprived of sleep.


    The body releases a steroid hormone called cortisol to activate our “flight-or-fight” responses to counteract acutely stressful situations. Cortisol stimulates the release of blood glucose by breaking down its storage form, glycogen. If youve experienced a stressful week, good chances are your blood sugars may be slightly higher than normal.


    Because glucose fluctuates after meals, we recommend fasting for a full 12 hours prior to getting a blood test for an accurate reading. This means water only, not even black coffee. People react differently to coffee so we suggest to err on the side of caution and stick to just water.

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