What’s the Difference Between Hemoglobin A1c and Blood Sugar?

Dr Jedha, Host

Hello wonderful people, Dr Jedha here and thanks for joining me for episode 74. We have talked about blood sugar levels quite a bit throughout various podcast episodes, but it’s always good to take a refresher, no matter how long you may have been living with diabetes. 

01:21

It’s also important that we cover important blood sugar topics, as I see common questions coming up all the time and since everyone is at a different point in their journey, I understand all this blood sugar stuff can be confusing. 

For example, Lisa asked, what is A1c, and while that may seem like a silly question to some, there is no such thing as a silly question – if you don’t know you don’t know until you know, right. So never think any question is silly. In fact, if you have a question, please send it in a future Q & A episode. Head to Type2DiabetesTalk.com/message – I’d love to hear your question, as I’m sure all our listeners would too, as we always draw valuable insights from the questions people send in, so head to Type2DiabetesTalk.com/message to leave me a voice message or email.

Getting back to the topic of today, Lisa asked, what is A1c, we’re going to cover that. 

Rock said: “This article mentions reducing A1C from 10% to 7%. It also mentions metformin can reduce A1c by up to 1.5% at maximum dosage. I didn’t think A1c was a percentage of measurement. Please explain.” We’re going to talk about the different A1c measurements, as unfortunately these can be different depending where you live. 

Mike said: “I don’t understand my daily blood sugar readings and how that’s different to A1c.” This is another common question we get and we’ll be diving into that today. 

Georgina asked for advice about her numbers, sometimes being 7.6, another tie 9.8, then 6.7, then 5.2 – and feeling confused about what any of it means. Worst of all she asked her doctor and got no response but said she was getting fobbed off, which of course is not good and we certainly don’t want you to feel confused, because these are good questions. 

03:38

Just know you’re not alone in this. We’ve had many members who’ve had diabetes for 20 years and still haven’t fully understood what their numbers meant and how to use them to get better results. Unfortunately, most doctors aren’t great at explaining these things to you, which is why we love covering these topics on the podcast, for people at various stages of the journey, whether that be at risk of pre or T2Diabetes, newly diagnosed or living with diabetes a long time. 

Importantly, always ask questions, because that’s the only way you can understand your numbers and your health so you can be proactive to change it, if you want or need to. In any case, we are going to address this that Georgina was confused about as well, the issue with blood sugar fluctuations. 

04:45

Firstly, for those who might be newly acquainted with the realm of diabetes – newly diagnosed: you might hear the terms blood sugar and blood glucose used interchangeably. These are exactly the same thing, just different ways of expressing the same concept. So whether someone mentions blood sugar levels or blood glucose levels, rest assured, they’re talking about the same thing. 

Blood sugar, also known as blood glucose, is the amount of glucose circulating in your bloodstream at a given moment. With pre and T2diabetes or prediabetes, your blood sugar levels serve as a key indicator of how well your body is processing glucose or sugar – remember, these are the same thing.

Depending where you live, blood sugar levels are measured in units like milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). We always share both measurements on the podcast, since we have listeners from all over the world. 

Monitoring blood sugar levels provides immediate feedback on how your nutrition and lifestyle are affecting your body. 

The two most common times to check blood sugar levels are:

• Fasting (this is your morning readings before eating): This reading helps establish a baseline for the day; and the other most common reading is:
• Two hours after meals (that’s called your postprandial readings): These measurements show how your body is managing the food you just ate.

Many people use a glucose meter that performs a simple finger-prick to draw a small amount of blood to get a test result; and some people use a continuous glucose monitor (or CGM) to measure their blood sugar. These tools provide real-time data to guide your decisions.

06:39

I’m not going to go into detail on the specific numbers on this podcast, because we’ve covered normal blood sugar levels and goals in episode 11, so after listening today, go back and listen to that episode as well. 

In brief, a normal fasting level, remember that’s your morning reading first thing when you wake up before breakfast – normal is 70-99 mg/dL or 4.0 and 6.0 mmol/L. After meals, a normal postprandial level is under 140 mg/dL or under 7.8 mmol/L. Your blood sugar levels may be higher than this now, but over time these are your goals, to get your levels within this normal range or as close to the normal range as possible

Reaching these targets consistently indicates optimal blood sugar management and reduced risk of complications.

07:42

Now, something that comes up quite a bit is confusion about numbers being all over the place. So here’s the thing: It is normal for blood sugar to fluctuate, that happens for everyone, whether they have diabetes or not. Blood sugar levels are dynamic, constantly shifting based on various different factors.

• Diet: What and when you eat has the most immediate impact. For example, foods high in carbohydrates can cause spikes.
• Exercise: Physical activity helps lower blood sugar by increasing insulin sensitivity and encouraging glucose uptake by muscles, but sometimes it can cause a temporary rise in blood sugar.
• Sleep: Poor or insufficient sleep can disrupt hormonal balance, leading to higher levels.
• Stress: Emotional or physical stress triggers cortisol, which can elevate blood sugar.
• Illness or Medications: Being unwell or taking certain medications can also impact your numbers.

These fluctuations are normal, but the goal is to aim for those normal target ranges, as much as possible. Over time, patterns in your readings can provide valuable insights into what’s working and what might need adjustment.

Daily blood sugar readings offer a real-time snapshot of your control or how your body might be responding to different things. For example, if your post-meal reading is higher than your target, you can adjust your portion sizes or food choices the next time. Similarly, if you see stable readings after a new routine, like adding a short walk after dinner, it’s a sign that change is helping. Monitoring your levels gives you immediate feedback that you can use to your advantage. The important thing is, if you notice readings that are higher than they should be, don’t panic. Readings provide useful information to you so you can make adjustments, that’s why daily readings are so useful. 

By focusing on these daily numbers, you can make proactive adjustments to your nutrition and diet, exercise and overall lifestyle.

10:25

So what about A1c, what is that?

A1c, also referred to as hemoglobin A1c, HbA1c, or glycated hemoglobin, is a blood test that provides an average of your blood sugar levels over the past three months. It’s a key marker used by your doctor or the healthcare providers you work with to assess your long-term glucose control.

Here’s how it works:

• Hemoglobin is the protein in red blood cells responsible for carrying oxygen.
• When glucose enters your bloodstream, it attaches to hemoglobin through a process called glycosylation.
• The A1c test measures the percentage of hemoglobin coated with sugar (glycated hemoglobin, or in more simple terms, the amount of sugar on the blood).
• Since red blood cells live approximately three months, this test reflects an average of your blood sugar over that timeframe.

A1c offers you a broader picture of how things are going. Unlike daily blood sugar readings, which show immediate and often fluctuating values, the A1c test provides a more stable and comprehensive view of your blood sugar control. It averages both the highs and lows of your daily readings, offering an objective measure of how well you’re managing your blood sugar over time. 

And here’s the thing: If you’re monitoring your daily levels at home, you can see a difference in your blood sugar numbers within a few days, even one day or one meal, if you know what adjustments to make and what numbers you’re looking at. For A1c that’s not the case, you can’t influence A1c by changing one meal because it is the average of your blood sugar over that 3-month period. Yes, you can influence A1c, of course you can bring it down if it’s high, but you need to allow a few months to see a noticeable difference. 

12:51

Let’s talk about A1c numbers, which is also another area of confusion because these are measured differently all around the world. This is so frustrating but that’s the way it is, so let me explain this. 

The results of an A1c test is often given as a percentage and the normal A1c range is set at 4-5.7% in the US and 4-6% in most other countries. In the UK and some other places, doctors will report your A1c test using millimoles per mole. So for A1c a normal level is under 42. 

With T2Diabetes, your initial target is under 7% or under 53, then work toward a level under 6% or 42. For prediabetes, you’re ideally aiming for an A1c level under 5.7% or 39.

Knowing your A1c helps you gauge the effectiveness of your overall diabetes management. Your A1c level also helps you understand your risk of long-term complications such as nerve damage, eye problems, or heart disease. Research shows that lowering your A1c by just 1% can significantly reduce these risks. Even lowering A1c by 0.1% can reduce risk of complications, so don’t undervalue any progress you make, it’s all valuable, any reduction is valuable.

15:36

Now that we’ve cleared up what blood sugar and A1c is and the normal target ranges, you may still be wondering, well, how do A1c and blood sugar relate.

The A1c and daily blood sugar readings are interconnected. If you maintain good control of your daily blood sugar levels—keeping them within target ranges consistently—your A1c will naturally improve. On the other hand, frequent high blood sugar readings will cause your A1c to rise. That’s the simple equation. 

High blood sugar readings on a daily basis equals high A1c levels. Lower blood sugar readings on a daily basis equals lower A1c levels. 

It’s important to note, however, that A1c is not influenced by short-term spikes or dips in your blood sugar. For example, if you had a few high readings due to stress or illness or a high sugar meal, it’s unlikely to significantly impact your A1c unless those highs are consistent over weeks or months.

By using the A1c test as a long-term marker and combining it with daily blood sugar monitoring, you’ll have a clearer picture of where you stand and what steps to take to stay on track.

16:55

So let’s clarify the key differences between blood sugar and A1c

Daily blood sugar reflects the glucose level in your bloodstream at a specific moment. It can vary throughout the day, influenced by meals, physical activity, stress, sleep,  medications and other things. The purpose of daily blood sugar readings is they provide you with immediate feedback, helping you make real-time adjustments to your nutrition and diet or other lifestyle factors. For example, a post-meal reading can indicate how well your body handled the food you just ate.

A1c reflects the average of your blood sugar levels over a 3-month period by measuring the percentage of glycated hemoglobin (sugar-coated red blood cells). The purpose of A1c is to offer you a long-term view of your overall blood sugar management, accounting all of your daily blood sugar readings collectively. An A1c test is less affected by short-term factors like a single meal. Unlike daily readings, A1c is more stable and serves as an indicator of overall blood sugar management and your risk for complications.

So for comparison, daily blood sugar is your immediate, real-time snapshot; A1c is your average over 3 months. Daily blood sugar can be tested multiple times a day using a glucose monitor at home or a CGM; A1c is tested every 3-6 months via a blood draw, usually ordered by your doctor and conducted at the pathology lab. Daily blood sugar levels fluctuate daily, A1c levels are stable over time. Daily blood sugar is very useful for that immediate feedback to make short-term adjustments; A1c is a long-term progress assessment. 

Both of these types of measurements are important and useful. 

• Blood Sugar: Helps you make quick, actionable changes to manage your condition on a daily basis. For instance, if you notice high post-meal readings, you can adjust portion sizes or the types of foods you had in your meal.
• A1c: Serves as the “big picture” marker of your glucose control and indicates how effective your overall management plan is. It also predicts your risk for diabetes-related complications. A1c doesn’t account for variability, which is why it’s still useful to monitor daily readings.

Together, daily blood sugar monitoring and A1c testing complement each other. Think of it like this: blood sugar readings are individual puzzle pieces, while A1c is the completed picture. Both are essential for understanding your progress and guiding your next steps.

20:48

Now, earlier in the podcast we established the two most common blood sugar measurements are taken fasting, in the morning and after meals, postprandial levels. I do want to add an important thing here. Most people measure only fasting blood sugar levels and often doctors recommend this test, which can be very confusing for people. Yes, seeing how fasting levels are traveling over time is important. They can be more simple to measure because you take them consistently first thing in the morning, which makes remembering to do it easier. But, morning levels are often high in pre and T2diabetes and they can be one of the last tests to come into the normal range, so it’s better not to worry yourself about those numbers. When it comes to A1c, your after meal levels are actually more important.

If your after meal levels are tracking up around 190-200 or 10.6-11, your A1c is going to be around 8.5%. If your after-meal postprandial levels are up at 180 or 10, your A1c is going to be around 7.5%. If you’re aiming your target range for your after meal levels, under 140 or 7.8 after meals, then your A1c is going to come down over time, within the normal range, under 6%. There is a connection and relationship between A1c and after meal postprandial blood sugar levels. So, if you focus on that, you’re going to make a lot more progress in terms of your A1c. Remember, you want your levels two-hours after meals, your postprandial levels to be under 140 or 7.8.

So, I hope this episode has helped clear up some of the confusion around these important measurements and given you actionable insights to start using your numbers more effectively. Remember, daily blood sugar readings provide you with immediate feedback to guide your decisions, while A1c gives you a long-term view of your overall progress. Together, they create a complete picture of how things are going for you and whether you need to be more proactive with your nutrition and lifestyle. 

If you still have questions, head over to Type2DiabetesTalk.com/message and we’ll be sure to include it in a future Q&A episode or to cover it as a topic. 

Until next time, take care of yourself, stay consistent, and know that every step forward is a step toward better health. 

Dr Jedha, over and out.