Hemoglobin A1C (“HbA1c” or simply “A1c”) can be described as the standard used to measure blood sugar control in patients who have diabetes. A1C measures blood sugar levels over 2 to 3 months, and through studies such as DCCT and UKPDS, higher A1C concentrations have proven to be associated with the danger of developing complications related to diabetes (kidney and nerve diseases). For every one percent decrease in A1C, there is substantial protection from these conditions.
But, on average over time, A1C cannot capture critical details such as time spent within a range of target (70-180 mg/dl) and in the lower that range (less than 70 mg/dl).
This article explains the reasons A1C is utilized and the variables that could lead to falsely low or high values. In the next article, we will discuss time-in-range, blood sugar variation, and methods to quantify and interpret them.
What exactly is A1C and the reason it is used?
A1C measures a person's typical blood sugar levels over a two—to three-month period. It's one indicator of whether blood glucose levels are managed and is a sign of diabetes management.
Although A1Cs don't provide daily information, it is linked to a lower likelihood for “microvascular” complications like kidney problems (nephropathy) as well as loss of vision (retinopathy) and damaged nerves (neuropathy). In the same way high A1Cs can result in “macrovascular” complications like heart disease.
A1C can be determined in a laboratory using routine blood tests or the countertop machine found in an office of a doctor (and certain pharmacies) by using the fingerstick.
A1C is a measure of the percent of “glycated hemoglobin” which is a term used to describe hemoglobin red blood cells that have sugar attached to them. If a person is consistently having more blood sugar levels, the A1C levels will go higher because more red blood cells have been covered with sugar. The test represents an average of between 2 and 3 months because the connection is permanent once a blood cell is coated with sugar. It's only when the red blood cells are “recycled” (which occurs at intervals of 2 and 3 months) that the sugar coating is removed.
What is “normal” A1C levels for those who don't suffer from diabetes?
In general generally, typically, high A1C values are indicative of an elevated blood sugar level and indicate that a person may be at risk or might be suffering from diabetes.
A1C Chart
A1C < 5.7%
- What It Means: Normal (minimal Risk for Type 2 Diabetes)
- Your average blood glucose level for the last 2-3 months is in the same range as someone who doesn’t have diabetes.
A1C Between 5.7% to 6.4%
- What It Means: “Prediabetes”, meaning at risk for developing type 2 diabetes
- Your average blood glucose level is higher than normal, but not high enough to be considered type 2 diabetes.
A1C > 6.5%
- What It Means: Diagnosed diabetes
- Your average blood glucose level for the last 2-3 months is at the level of someone with type 2 diabetes.
Make sure you get a regular A1C test, especially if you think you might be at risk for diabetes.
What is the A1C objective for people who have diagnosed diabetes?
A1Cs that are less than 6.5 percent or 7 percent is the ideal goal for a lot of people suffering from diabetes. As each individual with diabetes is different, however doctors are advised to determine individual A1C goals. For instance, the goals could vary based on age and other health conditions.
What are the effects of age on A1C?
A1C measures the management of diabetes, and the A1C of your blood won't change when you get older. But as you age, your A1C and diabetes management strategies goals can change. For instance, younger individuals may focus more on reducing the risk of long-term health problems, whereas older people might focus more on avoiding extreme lows. Consult your physician If you're interested in learning more about how age can affect the A1C levels of your blood.
Where are the areas where A1C false or even inaccurate?
A lot of progress has been made in establishing a standard and increasing precision of A1C test through the National Glycohemoglobin Standardization Program (NGSP). The results of a non-NGSP accredited lab might not be as accurate. Based on the type of machine and the lab, one A1C test could be able to have an 0.5 percent error margin which means that the “true” value could be 0.5 percent lower or higher than the actual A1C. For instance, if a laboratory report indicates the A1C measurement of 7.0 percent, the real A1C value could be between 6.5 percent to 7.5 percent.
A1C is determined by the person's red blood cells turnover (the life span of the red blood cell) and the amount of sugar in each cell. Certain conditions, like hemoglobin variants, kidney disease and certain forms of anemia, as well as certain medications and vitamins, affect the red blood cell's turnover which can lead to inaccurate A1C results. Click here to navigate to a list with factors that affect A1C.
The relation of A1C values and the average blood sugar levels may differ significantly from person to. When studies are conducted using Continuous glucose monitoring (CGM) continuous blood sugar levels are evaluated against a measured A1C. The results show a wide range between individuals. For example the 8percent A1C measurement in one individual could indicate the average blood sugar reading of 140 mg/dl whereas in another, it might be 220 mg/dl. This is due to the individual different ways in which blood sugars are able to bind to the life span of the red blood cells.
A1C to Blood Sugar Conversion
- A1C = 5: 80 mg/dl, 4.7 mmol/L
- A1C = 6: 115 mg/dl, 6.3 mmol/L
- A1C = 7: 150 mg/dl, 8.2 mmol/L
- A1C = 8: 180 mg/dl, 10 mmol/L
- A1C = 9: 215 mg/dl, 11.9 mmol/L
- A1C = 10: 250 mg/dl, 13.7 mmol/L
- A1C = 11: 280 mg/dl, 15.6 mmol/L
- A1C = 12: 315 mg/dl, 17.4 mmol/L
- A1C = 13: 350 mg/dl, 19.3 mmol/L
- A1C = 14: 380 mg/dl, 21.1 mmol/L
What are the options for you If an A1C test is not reliable or adequate?
In addition to A1C tests The most widely used tests of blood sugar include:
- The oral glucose tolerance test (OGTT).
- CGM.
- Self-monitored tests for blood sugar.
The OGTT is a diagnostic instrument for that can detect diabetes and prediabetes. It also evaluates the response of a person to eating an volume of sugar. After drinking the sugar beverage your blood sugar level is analyzed after two hours. Anything below 140 mg/dl is deemed “normal,” between 140 mg/dl and 200 mg/dl is considered for prediabetes, or impaired tolerance to glucose and anything above 200 mg/dl is a sign of the presence of diabetes. It's not recommended for monitoring treatment for diabetes.
For people with diabetes that is well-established, CGM has the advantage of observing the levels of blood sugar all period of the day (every 5- 15 mins) It also provides more thorough information about the time the range of low blood sugars and the presence of high levels.
If CGM isn't available, frequent fingersticks using a blood glucose monitor – for instance, at the time of waking, before or after meals, and prior to bedtime – could show when the levels of blood sugar are high or low and maintaining their normal range.
What is important to keep in mind when it comes to A1C?
If you have diabetes, it's crucial to consider the fact that A1C isn't an actual “grade” for managing diabetes however, it is a valuable assessment tool for you as well as your medical provider can use to inform your choices and evaluate the likelihood of developing complications.
Non-glycemic variables that may affect A1C:
Although there are a myriad of unobserved aspects that can affect A1C however, the information contained listed below isn't meant to discredit A1C. A1C test. Instead, understanding how certain circumstances and conditions can affect A1C levels is an essential aspect of making use of A1C as a measure of managing diabetes.
A lot of ailments that impact A1C results can be attributed to changes in the metabolism in red blood cells and consequently, most notably, forms of anemia. The treatment of anemia can affect the A1C results as well.
Anemia that is not treated
Anemia that is not treated may be due to deficiencies in iron or vitamin B-12 deficiency. Untreated anemia may cause falsely higher A1C numbers due to the decreased creation of blood red cells. For a test to determine if you have anemia, consult your doctor about the complete blood count (CBC) test.
Asplenia (decreased the function of the spleen)
The spleen plays a role in removing and producing red blood cells. The decreased function of the spleen could result from surgery removal, congenital diseases or blood disorders like sickle cell disorder. This can lead to a falsely increasing A1C. Asplenia is diagnosed with MRI or echocardiogram, chest radiograph, or by a screening test.
Blood loss and transfusions
The body's reaction in response to a recent loss of blood (create larger blood cell) or a blood transfusion may cause a falsely lower A1C but the next A1C test will be an accurate reading. Tell your healthcare professional that you've had an injection of blood.
A liver condition called cirrhosis
Cirrhosis is a term used to describe chronic liver damage that causes scarring. Cirrhosis, as well as impacting response to diabetes-lowering drugs which includes insulin, may be misleadingly lowering A1C values. Talk to your healthcare professional for a liver exam.
Hemoglobinopathy and Thalassemia
Abnormal hemoglobin levels characterize hemoglobinopathy, and thalassemia refers to the decreased production of functional hemoglobin. In the event of an abnormal form of hemoglobin, it may cause an increase or decrease in A1C values. Thalassemia could cause misleadingly low A1C numbers due to the early degeneration of the red blood cells. Discuss with your healthcare provider that you know of relatives with Thalassemia.
Hemolysis (rapid destruction of red blood cells)
Hemolysis can falsely reduce A1C values due to the decreased life span of red blood cells. This could be due to an unsuitable immune response or synthetic heart valves.
Hypothyroidism that is not treated (low amounts of the hormone thyroid)
Hypothyroidism can falsely raise A1C levels, whereas treatments with thyroid hormone could reduce A1C. Consult your doctor to take blood tests to evaluate thyroid function.
Pregnancy
The shorter lifespan of red blood cells and an increase in production of red blood cells can be in error lower A1C values both in the late and early stages of pregnancy. Consider taking the glucose test in your mouth which can be used to diagnose gestational diabetes. One common procedure for women who are pregnant and suffer from diabetes is to take CGM.
Uremia (high levels of waste (normally removed by kidneys) in blood)
Untreated uremia can misleadingly increase A1C values. Dialysis is a treatment for Uremia. In this situation, A1C isn't an appropriate test.
Medications
The medications that can misleadly raise A1C include:
- Opioids (pain relief agents) (pain relievers): Duragesic (fentanyl) Norco/Vicodin (hydrocodone), Dilaudid (hydromorphone) Astramorph/Avinza (morphine) or OxyContin/Percocet (oxycodone)
- For long-term use, you must take 500 mg of aspirin per day or more
The medications that could misleadly lower A1C are:
- Erythropoietin (EPO)
- Azcone (dapsone)
- Virazole/Rebetol/Copegus (ribavirin)
- HIV medication (NRTIs): Emtriva, Epivir, Retrovir, Videx-EC, Viread, Zerit, or Ziagen
Always talk about the proper usage of opioids for pain, and the possible effects they could have on A1C, too. Inform your doctor that you're using any of these medications prior to taking your A1C test.