We are always told that having a low A1c is an important goal in our diabetes management, but do you know why? Do you know what a good A1c target is, how to lower your A1c, and how quickly you can lower your A1c safely?

These are the questions I will answer in this comprehensive guide on what A1c is, how to lower your A1c, and why achieving a low A1c isn’t the only (or necessarily the best) goal when it comes to diabetes management.

How to lower your A1c

What is A1c?

A1c, hemoglobin A1c, HbA1c or glycohemoglobin test (all different names for the same thing) is a blood test that measures your average blood sugar over the last 2-3 months. It’s not an “even average,” but an average where your blood sugars over the last few weeks count a little more than your blood sugars 2-3 months ago.

According to the National Institute of Diabetes & Digestive & Kidney Diseases:

“The A1c test is based on the attachment of glucose to hemoglobin, the protein in red blood cells that carries oxygen. In the body, red blood cells are constantly forming and dying, but typically they live for about three months. Thus, the A1c test reflects the average of a person’s blood glucose levels over the past three months. The A1c test result is reported as a percentage. The higher the percentage, the higher a person’s blood glucose levels have been. A normal A1c level is below 5.7 percent.”

It’s important to note here that the term “normal A1c level” in this context refers to people without diabetes. I will get back to what a “normal A1c level” is for people living with diabetes below.

How to test your A1c

Your doctor or endocrinologist should test your A1c regularly (typically every 3-6 months). The doctor simply pricks your finger (or ear if you prefer) and takes a tiny blood sample. If the doctor’s office has an A1c kit, you should get your result before your consultation is over.

You can also buy home A1c kits (no prescription required) and do the test yourself. Home A1c kits can be useful if you go for more than three months between doctor visits and want to keep an eye on how your A1c is developing yourself.

The home kits are generally accurate within plus/minus 0.5 percentage points, which is more than good enough to give you a trustworthy result. The downside of the home kits is that they require a larger amount of blood (four large drops) than a regular blood sugar test, and if you don’t apply enough blood, you’ll get an error message and will have lost a test strip.

You can find home test kits on Amazon and in some pharmacies.

Why you should care about your A1c

Multiple studies have shown that high average blood sugars increase the risk of diabetes-related complications. Lowering your A1c to the recommended range will reduce the risk of diabetes-related complications significantly:

  • Eye disease risk is reduced by 76%
  • Kidney disease risk is reduced by 50%
  • Nerve disease risk is reduced by 60%
  • Any cardiovascular disease event risk is reduced by 42%
  • Nonfatal heart attack, stroke, or risk of death from cardiovascular causes is reduced by 57%

Achieving an A1c in the recommended range is, therefore, one of the most important things you can do to improve your long-term health when you live with diabetes.

However, the closer you get to the recommended A1c target, the less benefit you will get from lowering your A1c further. Taking your A1c from 12% to 11% makes a big difference while lowering your A1c from 7% to 6% provides a much smaller benefit. In fact, lowering your A1c too much may not be a good idea if it means that you increase how often you experience hypoglycemia (low blood sugar).

I will explain why “time-in-range” is just as important as a low A1c later in this guide.

What is a “normal” A1c?

Now that you have your A1c number, let’s look at what that number actually tells you. The American Diabetes Association has established the following guidelines:

A1c levels for people with and without diabetes

This does NOT mean that you need an A1c of less than 5.7% if you’re living with diabetes. It means that if you do NOT live with diabetes, your A1c is expected to be below 5.7%. There are different recommendations for what an appropriate A1c is for people living with diabetes.

I had a chance to asked Dr. Anne Peters, MD, Director, USC Clinical Diabetes Program and Professor of Clinical Medicine Keck School of Medicine of USC as well as Gary Scheiner, MS, CDE, owner and Clinical Director of Integrated Diabetes Services and author of Think Like a Pancreas, what their perspectives are on a good A1c target:

Dr. Peters:

The A1c target should be whatever is best given the person’s clinical situation. For athletes, too many lows can limit performance, for someone who is pregnant it should be <6%, for an older person the target should be higher. I generally think an A1c target of 6.0 – 7.0% is ideal and data shows that going below 7% has fairly little impact on complications. Basically, I’d rather see someone with an A1c of 6.9% and low blood sugar variability than an A1c of 6.2% with lots of variability

Gary Scheiner, MS, CDE:

“A1c goals should be individualized based on the individual capabilities, risks, and prior experiences. For example, we generally aim for very tight A1c levels during pregnancy and more conservative targets in young children and the elderly. Someone with significant hypoglycemia unawareness and a history of severe lows should target a higher A1c than someone who can detect and manage their lows more effectively. And certainly, someone who has been running A1c’s in double digits for quite some time should not be targeting an A1c of 6%… better to set modest, realistic, achievable goals.”

In their Standards of Medical Care in Diabetes, the American Diabetes Association recommends an A1c target of below 7% for adults living with diabetes. An A1c of 7% roughly translates to an average blood sugar of 154 mg/dl (8.6 mmol/L) as you can see from this conversion chart.

Table of conversions between average blood sugar and A1c

To learn more about blood sugar levels, please read “What are Normal Blood Sugar Levels“.

A1c vs. Time-in-Range

A1c has long been considered the best measure of diabetes management because it was the most accurate tool to observe long-term blood sugar trends. This has changed with the introduction of Continuous Glucose Monitoring (CGM). By using a CGM, you can now get a very accurate picture of not only your average blood sugar, but your blood sugar fluctuations as well.

This makes it possible to track another key component of diabetes management: Time-in-Range.

Time-in-range refers to the percentage of time in which your blood sugar is within a specific range. To see why time-in-range is important, take a look at the three lines in the graph below. All three lines show an average blood sugar of about 154 mg/dl (which equals an A1c of about 7%) but with very different fluctuations. I think we would all prefer our blood sugar to follow line 3 rather than line 1.

Graph showing 3 different blood sugar curves with same A1c but very different time in range

Graph used with permission from Diatribe

Some guidelines state that your blood sugar range should be set to 70-180 mg/dl (3.9-10 mmol/l), but you may find that to be too large or small of a range for you. According to this interview with several diabetes experts, most recommend that you spend less than 3% of the time below 70 mg/dl (3.9 mmol/l) and less than 1% of the time below 53 mg/dl (3 mmol/l). However, they also agree that the actual time spent in range needs to be individualized.

On average, the experts didn’t expect the general diabetes population to be in range more than 50% of the time at most, so talking about incremental improvement probably makes more sense than setting a fixed number.

How to measure Time-in-Range

If you wear a Continuous Glucose Monitor (CGM), your time-in-range should be listed when you download your data (as in the example from a Dexcom CGM below). If you don’t use a CGM, all you can do is look at your manual blood sugar tests and pay attention to your amount of high and low blood sugars. What’s an acceptable high and low is something you have to discuss with your medical team.

Screenshot from a Dexcom CGM showing time in range

What is more important: a low A1c or a high Time-in-Range?

Optimally, you’d have an A1c below 7% accompanied by a low blood sugar variance (high time-in-range). A good general guideline is:

  • The higher your A1c, the more important it is to focus on getting it down.
  • The lower your A1c, the more important time-in-range becomes.

If your A1c is below 6-7%, focusing on increasing your time-in-range will probably have a larger positive health impact than lowering your A1c further.

So is A1c a bad way to gauge whether your diabetes management is on track? Not necessarily, but to quote Gary Scheiner, MS, CDE:

“I’ve never been a huge fan of using A1c to gauge the “quality” of a person’s glucose control, simply because it represents an average… and an average can reflect lots of highs and lows rather than time spent within one’s target range. However, it’s not something we can ignore either since there is a correlation between A1c and the risk of long-term complications.”

Can your A1c be too low?

As described above, the answer to this question depends almost entirely on how often you experience hypoglycemia (low blood sugar). If you (almost) never experience hypoglycemia, your A1c technically cannot be too low. Some people achieve A1c levels below 5% by following a very strict diabetes management and diet regimen and have almost no blood sugar fluctuations.

HOWEVER, if you often experience hypoglycemia, that will result in an “artificial” low A1c reading because your hypoglycemia events are lowering your blood sugar average. In that case, focusing on increasing time-in-range is much more important than further lowering your A1c. In fact, you may even benefit from a slightly higher A1c with fewer blood sugar fluctuations.

It’s also important to note that lowering your A1c below the recommended range of 6-7% hasn’t been proven to provide any health benefits. Therefore, a very low A1c shouldn’t be a goal in itself.

How to lower your A1c

Now that you have a thorough understanding of A1c and time-in-range, as well as why looking at your A1c in isolation isn’t optimal, the obvious question is:

How do you lower your A1c while improving or sustaining your time-in-range?

I will cover the four most important things you can do below but it’s always recommended that you start by having a conversation with your medical team before making changes to your diabetes management.

Identify the main “pain points”

Whether you are self-managing your diabetes or work closely with your medical team, the first step should always be to try to identify the main “pain points” or reasons why your A1c is higher than you’d like. The only real way of doing this is by tracking your blood sugars very closely.

If you wear a Continuous Glucose Monitor, you can look at your 7-day, 30-day, and 90-day data to see if you can spot any trends. For example, you might find that you are running high from 1-5 AM every night, every morning (hello Dawn Phenomenon) or every day after meals. Or perhaps you always go low after exercise. We all have different blood sugar patterns.

It’s also very possible that you simply are running your blood sugar a little too high all the time and could benefit from adjusting your diabetes medication. Identifying patterns like that makes it possible to pinpoint areas of potential improvement so you can start making a plan for how to limit your high and low blood sugars.

If you rely on manual blood sugar testing, it’s a little trickier since most people don’t test every five minutes. What I would recommend is increasing how often you test for a while, and maybe even test during the night if you wake up anyway. Most meters allow you to download data to your computer, or you can upload the data to one of various app-based platforms. This can help you see the data in a more cohesive way so you can start looking for trends.

Create a plan for your diabetes management

Now that you have a better idea of what your “pain points” are, you can start making changes to your diabetes management.

Your doctor may suggest a different medication regime. For example, some people (regardless of their type of diabetes) are prescribed Metformin to help with Dawn Phenomenon (morning blood sugar spikes not related to eating). Others may need adjustments to insulin dosing, etc.

If you’re insulin-dependent and consistently have high blood sugars in the morning, getting your blood sugar fluctuations and A1c down might be as simple as adjusting your nighttime basal insulin. Or, if you run high every day after meals, your carb-to-insulin ratio might be off, and adjusting that could be what sets you on a path of a lower A1c. Until you collect the data and do the analysis, you have no way of knowing this.

I want to make an important point here: increasing your diabetes medication is not a sign of failure! It’s often the best (and sometimes only) way to control your blood sugar and bring down your A1c.

I adjust my insulin up and down all the time when I change my diet or exercise routine. Adjusting your medication is an important tool in your diabetes toolbox and something you should always discuss with your medical team.

Understand nutrition and adjust your diet

What you choose to eat and drink can have a major impact on not only your waistline, mood, and well-being, but also on your blood sugar levels.

All macronutrients (carbohydrates, proteins, and fats) can affect your blood sugar to some degree so developing a good understanding of how they affect your blood sugar will enable you to be proactive and prevent blood sugar swings.

Carbohydrates (carbs)

Carbohydrates have the greatest impact on your blood sugar, which is why many people with diabetes can benefit from following a low- to medium-carb diet (or even a ketogenic diet). The fewer carbs you eat, the less insulin you need to take, which makes diabetes management easier.

However, you don’t have to follow a low-carb diet if it doesn’t work for you – physically or mentally. As I wrote in my post about which diet is best for people with diabetes, it is very possible to have great blood sugar control on a medium (or even high) carb diet, as long as you experiment, take notes, and learn to take the right amounts of insulin for the carbs you are eating.

It is very important to realize that we all react differently to carbs so you have to find the diet and foods that are right for you.

As an example, people react very differently to carbs like oats or sweet potato. Some people can eat oats with only a small increase in blood sugar while others see a quick spike. By simply knowing this, people struggling with a certain type of carb can choose to reduce their consumption or cut it out of their diet altogether.

Protein & fats

While carbs affect blood sugar most significantly, protein and fat also have an impact. Some, like Dr. Sheri Colberg, even think that simply looking at carbs when estimating blood sugar impact (and dosing insulin) is an outdated and inefficient way to perceive diabetes management and that you should focus more on total calories (read more here).

The key thing to be aware of is that when protein and especially fat is consumed with carbohydrates, the energy from the meal will be released more slowly, which means that your blood sugars will be impacted more slowly as well.

While I don’t believe your diabetes management should completely dictate how you live your life and which diet you choose to follow, it can be worth evaluating what food choices make life easier for you. By making a conscious choice of which type of nutrition plan to follow (the majority of the time), you can more easily establish healthy habits that will benefit not only your overall health but also your daily blood sugar levels, and thereby your A1c.

Increase activity (exercise)

While exercise is essential for building and maintaining good health and improving insulin sensitivity, it can be a double-edged sword if it constantly throws your blood sugars for a loop. Not only is that very frustrating, scary, and annoying, but it can also affect your A1c and time-in-range negatively.

The key is to understand how different types of exercise affect blood sugars and, if you use insulin, learn your formula for insulin and food around workouts.

Cardio

Cardio, such as brisk walking, jogging, swimming, biking, or dancing, are all excellent types of exercise, and as little as 20-30 minutes a day can make a significant difference when it comes to improving insulin resistance and managing blood sugar levels.

Not only does exercise reduce blood glucose during exercise, but it also improves your insulin sensitivity for hours after your workout, meaning that you need less insulin.

If you treat your diabetes with insulin, you will have to manage your insulin levels so you don’t experience exercise-induced hypoglycemia. This comes down to reducing your insulin significantly or consuming carbs before your workout.

In general, it should not be needed to “carb up” to do up to 60 minutes of steady-state cardio, but there can be situations where reducing insulin before exercise can’t be done, so additional carbohydrates must be consumed.

Resistance training

Adding resistance training to your daily routine, even if it’s just bodyweight exercise, can be instrumental in increasing your insulin sensitivity and lowering your A1c.

Whereas cardio will lower blood sugar during exercise and potentially up to 36 hours after exercise, resistance training can increase insulin sensitivity for much longer since muscles work as little “glucose tanks” and you’ll store more glucose in your muscles rather than sending it directly to your bloodstream. The more muscles you have, the better your insulin sensitivity.

Just be aware that most people will see an increase in blood sugars during resistance training (research was mainly done on people living with type 1 diabetes) rather than a decrease. The reason for the increase in blood sugar is that the improved insulin sensitivity from exercising is surpassed by your body’s increased glucose production. Your body is producing glucose faster than you can use it!

For a detailed guide to resistance training and diabetes, please see my article “How Resistance Training Affects Your Blood Sugar.”

Because resistance training is so effective at increasing your insulin sensitivity, it’s a great way to lower your blood sugar consistently. If you exercise regularly, the effect of exercising overlaps from one workout to the next and you essentially achieve a permanent increase in insulin sensitivity.

How quickly can you lower your A1c?

Because A1c is simply a measure of your average blood sugar over 2-3 months, it can (in theory) decrease by any amount over that time period. If you, from one day to the next, decreased your daily average blood sugar from 300 mg/dl (16.7 mmol/l) to 120 mg/dl (6.7 mmol/l), your A1c would decrease from 12% to 6% in around two months.

However, it may not be a good idea to lower your A1c so quickly, as I will explain below.

Why you shouldn’t lower your A1c too quickly

It can be a good idea to approach lowering your A1c with a bit of caution. Just as crash dieting isn’t healthy, there can be some serious health risks associated with lowering your A1c too quickly. I turned to Dr. Peters for an explanation:

If you lower your A1c too quickly, many bad things can happen. First, weight gain and total body swelling. Next, it can cause bleeding in the retina (back of the eyes) which can lead to blindness, and third, it can cause painful neuropathy that never goes away. It’s slightly different for newly diagnosed patients, but, in general, no one should try to go from an A1c of 10% to 6% quickly. Take slow steps. Wanting to get to a “low” number very fast only causes harm. Diabetes is a long-term disease, so slow steps to establish new habits that can last a lifetime is the way to go. Anything too sudden and the body reacts badly.”

My perspective on A1c as a person living with diabetes

I have a very ambivalent relationship with my A1c myself. I’ve been living with type 1 diabetes for over 20 years, and my A1c is not something I think about in my daily life. However, every three months when I see my endo, I get a little anxious because receiving your A1c can feel a lot like getting your diabetes report card.

And, quite honestly, that’s really silly. My A1c number doesn’t reflect what’s been going on in my life for the last three months. It doesn’t tell me how much effort I’ve put into managing my diabetes and it does not define me as a person. It’s a good source of information, nothing more.

Still, we tend to look at it and judge, good or bad, how we’ve done with our diabetes management. But we really shouldn’t!

That doesn’t mean that I think we shouldn’t get our A1c checked. I absolutely think we should, but we also need to understand what it means as well as why we should look beyond the A1c number. I hope this guide has given you the knowledge and tools to do so!