Having high glucose but a normal A1C can be a perplexing situation, as A1C is often used as a long-term measure of blood sugar control.
However, this discrepancy can occur for several reasons. Here are some possible causes:
- Timing of Glucose Measurement
- Fasting glucose spikes: Glucose levels fluctuate throughout the day, and a single high glucose reading (e.g., after meals) may not reflect overall trends. A1C reflects average blood sugar levels over the past 2-3 months, so temporary spikes may not elevate A1C.
- Stress or illness: Stress, infection, or acute illness can cause temporary high blood sugar, which may not be picked up by A1C if the event is recent.
- Postprandial Hyperglycemia: Some individuals experience postprandial hyperglycemia (high blood sugar after meals) while maintaining normal fasting glucose and A1C levels. This happens if blood sugar surges after eating but returns to normal quickly enough that it doesn’t affect the A1C reading significantly.
- Consuming high-carbohydrate or high-sugar meals can lead to temporary spikes in glucose, especially if the body struggles to process the large influx of sugar quickly.
- If your blood sugar tends to fluctuate rapidly (e.g., from low to high), A1C may remain normal because it represents an average. A few high spikes won’t necessarily raise A1C, which measures overall glucose exposure.
- Hemoglobin Disorders:
- Hemoglobinopathies (e.g., sickle cell anemia) or conditions like anemia can affect the lifespan of red blood cells. A1C measures glycation on red blood cells, so if their lifespan is shorter, the A1C may be falsely lower, despite elevated glucose.
- People with anemia or recent blood loss may also show a lower A1C because fewer old red blood cells are circulating to accumulate glucose.
- Early-Stage Diabetes: You may be in the early stages of diabetes or pre-diabetes, where fasting glucose and postprandial glucose are sometimes high, but A1C hasn’t yet risen. This stage is often marked by insulin resistance, which causes blood sugar to rise after meals.
- Medications (e.g., steroids, beta blockers) can cause temporary spikes in blood sugar without necessarily raising A1C if the usage is short-term.
- There may be some variability or discrepancies in how glucose and A1C are measured between labs. Occasionally, technical issues with the test can lead to inaccurate results.
- Some supplements, energy drinks, or foods may cause transient glucose elevations that may not significantly alter A1C, but lead to temporary hyperglycemia.
If high glucose persists despite a normal A1C, it’s essential to investigate further, possibly using continuous glucose monitoring (CGM) or frequent glucose testing to detect patterns and manage the condition effectively.
Here’s the video of Normal a1c but high fasting glucose.
Normal fasting glucose but high a1c
If you have a normal fasting glucose level but a high A1C, it is indeed unusual, as the A1C test reflects the average blood sugar level over the past two to three months, while fasting glucose measures your blood sugar level after an overnight fast.
A high A1C typically indicates poor long-term blood sugar control, while a normal fasting glucose level suggests good blood sugar control in the short term. However, there are a few potential explanations for this discrepancy:
- Recent changes in blood sugar levels: The A1C test reflects an average over several months, so if your blood sugar levels were previously elevated but have improved recently, your fasting glucose level might be normal while the A1C is still elevated due to the past high levels.
- A1C’s limitations: While the A1C test is a valuable tool for assessing long-term blood sugar control, it is not perfect. Factors such as certain medical conditions, variations in red blood cell lifespan, and certain genetic factors can affect the accuracy of the A1C test and result in discrepancies with fasting glucose levels.
- Laboratory error: It’s possible that there was an error in the A1C test result. A repeat test can help confirm whether the initial reading was accurate.
What is Hba1c?
Hba1c is the short name for Glycated Hemoglobin. Such hemoglobin form when HB bind with glucose by non-enzymatic glycation pathway, by releasing plasma glucose into hemoglobin.
How is Hba1c synthesis in our body?
Hba1c is formed by the non-enzymatic glycation pathway, by releasing plasma glucose into hemoglobin
What is the limitation of the Hba1c test?
Hba1c test is limited to a three-month average because the lifespan of red blood cells is four months (120 days). However, since all red blood cells do not undergo simultaneous rupture, HbA1C is taken as a specific for three months.
why is my fasting blood sugar high but my a1c is normal?
A normal A1C indicates good long-term blood sugar control, while a high fasting blood sugar suggests elevated blood sugar levels after an overnight fast. This discrepancy could be due to recent changes in blood sugar levels, lab error.
what if a1c is normal but fasting glucose high?
If your A1C is normal but your fasting glucose is high, it could indicate a condition such as impaired fasting glucose, the dawn phenomenon, the Somogyi effect, temporary fluctuations.
what does it mean if your fasting glucose is high but your a1c is normal?
If your fasting glucose is high but your A1C is normal, it may indicate a temporary or recent increase in blood sugar levels. While A1C provides an average of blood sugar control over the past two to three months.
It can be due to dawn phenomenon, the Somogyi effect, temporary fluctuations.
It can be due to dawn phenomenon, the Somogyi effect, temporary fluctuations.
what if my a1c is high?
If your A1C is high, it indicates that your average blood sugar levels have been elevated over the past two to three months. This could be a sign of poor blood sugar control and may suggest the presence of diabetes or prediabetes.
if my glucose is 120 what is my a1c?
The relationship between average blood glucose and A1C is not a direct conversion. However, an estimated A1C value of around 6.0% to 6.1% is often associated with a fasting glucose level of 120 mg/dL.
is a1c higher when fasting?
No, fasting itself does not directly impact A1C levels. A1C is a measure of average blood glucose levels over the past two to three months and is not influenced by short-term fasting.
how many hours fasting for hba1c?
Fasting is not required for an HbA1c test. The HbA1c test measures the average blood glucose level over the past two to three months.
how to calculate hba1c from fasting blood sugar?
To calculate an estimated HbA1c from a fasting blood sugar level:
1. Multiply the fasting blood sugar level by 28.7.
2. Subtract 46.7 from the result.
3. Divide the value obtained by 28.7.
1. Multiply the fasting blood sugar level by 28.7.
2. Subtract 46.7 from the result.
3. Divide the value obtained by 28.7.
Awful article. It contradicts itself on so many levels.
1st part:
Normal a1c but high Fasting Glucose
Normal a1c but high fasting glucose is the sign of Diabetes. This is the initial stage of diabetes Miletus because a1c shows the sugar level of previous weeks.
2nd part:
Fasting glucose high but a1c normal
If somebody has high fasting glucose but Hba1c is below 5.7% or normal. He needs not worry about his/her health. Fasting glucose can be rise due to some hormonal imbalance a few times. This rise in sugar will decline after a few hours.
Just awful.
I understand that high fasting BG with normal HbA1C is an indicator of Diabetes. As the offshore Medic on my facility, I perform Fitness to Work Physical Examinations on a regular basis for our workgroup, for which blood testing (lipid profile, blood sugar, and HbA1C) are all a part. Having access to the equipment, I test my own approximately every 6 months.
I am confused by my results. The high fasting BG (120-130mg/dl) began about 3 years ago, and has remained fairly constant. But the entire time period, the HbA1C has been 5.4-5.6%, no higher, no lower. I would think, if Diabetes were truly present, that I would see an increase in HbA1C readings by now.
I exercise regularly, eat a fairly well balanced diet (I’ve cut out processed sugar, bread, and keep starches like rice and potatoes to a minimum) and continually strive to battle the scourge of the upper-50 yo male, the spreading waistline. It’s a bit of a mystery to me.
I was diagnosed with prediabetes with 5.8 A1C and 120 FBS thereafter I controlled my carb intake, resultantly my A1C came down to 5.5 and then 5.3 but still my FBS is ranging in 120s. I am worried about such results as if i had diabetes.
I have lost 12 kg weight while continuously losing weight now i am worried about weight loss too. Is it due to walk, running and diet control due diabetes as the diabetic patient do face weight loss
Weight loss can be a symptom of diabetes, but it is not always the case. It is possible that your weight loss is due to your diet control and exercise routine, rather than diabetes. In fact, losing weight through a healthy diet and regular exercise is often recommended as a way to manage blood sugar levels and reduce the risk of developing diabetes.