10 Surprising Reasons Your A1C Is High Even Without Diabetes — Plus What You Can Do to Lower It Naturally

Imagine going in for a routine health checkup and hearing this from your doctor: “Your A1C is elevated.”

If you’re not diabetic, this news might be confusing—maybe even a little scary. After all, A1C is something you’ve probably heard mentioned mostly in the context of diabetes. So if you don’t have diabetes, why is your A1C high?

Here’s the surprising truth: a high A1C doesn’t always mean you’re diabetic. In fact, many people with elevated A1C are not officially diagnosed with diabetes at all. But that doesn’t mean you should ignore it.

In this article, we’ll explain what A1C actually measures, why it matters even if you’re not diabetic, and 10 science-backed reasons your A1C might be elevated anyway. Most importantly, you’ll learn what you can do about it—without medication in many cases.

Let’s break it down in plain English.

What Is A1C and Why Does It Matter?

A1C, also called HbA1c or glycated hemoglobin, is a blood test that tells you your average blood sugar levels over the past two to three months.

It works like this: when sugar (glucose) circulates in your bloodstream, some of it sticks to your red blood cells. The more sugar you have in your blood, the more of it sticks. Since red blood cells live for about three months, the A1C test captures a long-term snapshot of how much sugar has been circulating in your body—not just the levels from that day.

A1C is measured as a percentage:

• Below 5.7% is considered normal
• 5.7% to 6.4% is considered prediabetes
• 6.5% or higher is considered diabetes

But here’s the key: you can still have a high A1C and not technically be diabetic.

So, why does that matter?

Even if you’re not diabetic, elevated A1C levels can be a warning sign that your metabolic health is slipping. It may mean your body is struggling to keep blood sugar stable—something that can lead to fatigue, weight gain, inflammation, and over time, more serious problems like heart disease, kidney issues, and memory decline.

Let’s dive into 10 often-overlooked reasons your A1C might be elevated, even if you don’t have diabetes.

1. You Might Be in the Early Stages of Insulin Resistance or Prediabetes

One of the most common—and often missed—reasons for a high A1C is insulin resistance.

Insulin is a hormone that helps your cells absorb sugar from the bloodstream and use it for energy. But if your body starts resisting insulin’s effects, sugar stays in your blood longer. This can push your average levels higher—even if you feel fine and don’t have diabetes.

You might be in the “prediabetic” range, or just outside of it, but the trend is upward.

This early stage of metabolic dysfunction doesn’t come with obvious symptoms. You might still feel okay, even as your A1C creeps up year after year. Unfortunately, unless you take action, this can eventually lead to type 2 diabetes.

That’s why elevated A1C is like a check engine light for your metabolism—it’s not a diagnosis, but it’s a signal you shouldn’t ignore.

2. Your Test Result May Not Be Entirely Accurate

Believe it or not, lab results aren’t always perfect. Several factors can throw off your A1C test.

For example, if you have anemia, kidney disease, or certain hemoglobin variants (more common in people of African, Mediterranean, or Southeast Asian descent), your test could be falsely high or low.

A1C also assumes your red blood cells live for the standard 90–120 days. But if they live longer, more sugar builds up on them, pushing your A1C higher—even if your daily glucose isn’t that bad.

If your A1C result seems off, it’s worth asking your doctor about alternative tests like fructosamine or a continuous glucose monitor (CGM) for a more complete picture.

RELATED READ: How to Calculate and Understand Your A1C Levels (And Why It Matters for Blood Sugar & Health)

3. You’re Eating Too Many Hidden Carbs or Sugar Over Time

You might not be eating donuts every day, but carbs are sneaky.

Even seemingly healthy foods like whole-wheat bread, granola bars, fruit juice, or sushi can spike your blood sugar if you’re eating them often or in large amounts. When your body constantly has to deal with sugar highs, it wears down your insulin response over time. This leads to higher average blood sugar—and a higher A1C.

Many people who don’t consider themselves “unhealthy eaters” are still unknowingly fueling high A1C levels through:

• Excessive snacking
• Drinking fruit smoothies
• Eating low-fat, high-carb foods
• Not balancing carbs with protein and fat

You don’t need to cut carbs completely. But learning how they affect your blood sugar—and which types your body handles best—can make a big difference.

4. Chronic Stress Is Quietly Messing With Your Blood Sugar

Stress isn’t just a mental thing—it has a real, measurable effect on your body.

When you’re stressed, your body releases hormones like cortisol and adrenaline, which raise blood sugar levels so you have energy to deal with a “threat.” This is useful if you’re being chased by a lion. But not so great if the “threat” is traffic or a work deadline.

If you're constantly under stress, your body stays in this sugar-releasing state. Over time, your average blood sugar rises, and your A1C creeps up—even if your diet hasn’t changed much.

Many people overlook stress as a factor, but it can be a powerful driver of insulin resistance and metabolic issues.

5. You’re Not Sleeping Well (or Have Sleep Apnea)

You probably already know that poor sleep affects your mood and energy. But did you know it also impacts your blood sugar?

Sleep deprivation reduces insulin sensitivity, meaning your body doesn’t process sugar as effectively. Just a few nights of bad sleep can raise your blood sugar and insulin levels—enough to increase your A1C over time.

Sleep apnea, a condition where your breathing stops and starts during the night, is particularly harmful. It triggers frequent awakenings and oxygen drops, which stress your body and promote inflammation. People with undiagnosed sleep apnea often have elevated A1C without understanding why.

If you’re waking up tired, snoring loudly, or have trouble falling asleep, it’s worth getting your sleep evaluated.

RELATED READ: Zepbound: First FDA-Approved Medication for Sleep Apnea—How It Works and What It Means for You

6. Chronic Inflammation or Underlying Illness Is at Play

Inflammation is your body’s way of fighting back against stress, infection, or injury. But when it becomes chronic—due to things like poor diet, obesity, autoimmune issues, or gut problems—it can interfere with how your body uses insulin.

This insulin resistance leads to higher blood sugar, which in turn raises A1C.

You may not notice inflammation directly, but common symptoms include:

• Joint pain
• Fatigue
• Brain fog
• Skin issues
• Digestive problems

Conditions like PCOS, non-alcoholic fatty liver disease (NAFLD), and chronic infections can all subtly raise your A1C without triggering a diabetes diagnosis.

7. Your Medication Might Be Affecting Your A1C

Several common medications can raise blood sugar levels as a side effect. You might be taking these for reasons unrelated to your metabolism, but they can still cause your A1C to rise.

Examples include:

• Corticosteroids (like prednisone, used for inflammation)
• Antidepressants
• Beta-blockers (used for blood pressure or heart issues)
• Some antipsychotics

These medications affect how your body handles insulin or how sugar is stored and used. If you’ve noticed your A1C increasing after starting a new medication, bring it up with your doctor. There may be alternative options with fewer metabolic side effects.

8. Iron Deficiency or Anemia Can Skew Your Results

This one surprises a lot of people.

Certain types of anemia—especially iron deficiency anemia—can cause your A1C levels to appear higher than they truly are. This doesn’t necessarily mean your blood sugar is elevated. Instead, changes in red blood cell production and hemoglobin structure can lead to more glucose attaching to each red blood cell, which can falsely inflate your A1C reading. On the other hand, conditions that shorten red blood cell lifespan, like some forms of hemolytic anemia, can cause falsely low A1C results. So if you have anemia, your A1C may not accurately reflect your true average blood sugar levels.

9. Smoking, Alcohol, or Dehydration Might Be Contributing

Lifestyle habits like smoking and alcohol consumption can also affect your metabolic health—even if they don’t raise your blood sugar in obvious ways.

Smoking damages blood vessels and increases inflammation, which can impair insulin function. Alcohol, especially in excess, can throw off liver function, which plays a major role in glucose metabolism.

Even chronic dehydration can falsely elevate blood sugar readings in the short term and may subtly influence your A1C over time.

These factors may not seem directly related to A1C, but they impact the systems your body uses to regulate glucose.

10. Your Genetics and Ethnicity Might Play a Role

Some people naturally have slightly higher A1C levels due to genetic or ethnic differences in how their bodies process sugar or how long their red blood cells live.

For example, studies show that African American, Hispanic, and Asian populations may have higher average A1C levels compared to white populations, even when their actual blood sugar is the same.

This doesn’t mean you should ignore a high A1C, but it’s a good reason to combine it with other markers—like fasting glucose, insulin, or a CGM—when assessing your overall metabolic health.

Why Elevated A1C Still Matters (Even If You’re Not Diabetic)

Many people think, “Well, I don’t have diabetes, so I’m probably fine.” But A1C is more than just a diabetes test—it’s a marker of how your body is handling sugar over time.

Even if you're not diabetic, elevated A1C levels can:

• Increase your risk of heart disease
• Accelerate aging and cognitive decline
• Promote fat storage, especially around the belly
• Trigger chronic inflammation
• Lead to fatigue, low energy, and brain fog

So while a high A1C doesn’t mean you need insulin injections, it does mean your metabolic engine isn’t running as smoothly as it could.

And the good news? There’s a lot you can do to fix that.

RELATED READ: Normal Blood Sugar Levels by Age: Glucose Charts & What They Mean for Your Health

How to Lower Your A1C Naturally—Even Without Medication

You don’t need to go on a fad diet or take a bunch of supplements to improve your A1C. In many cases, simple, sustainable lifestyle changes are enough to bring it down.

Here are some of the most effective ways:

1. Eat a balanced diet with plenty of fiber, healthy fats, and protein. Cut back on refined carbs and added sugars.
2. Move your body daily, even if it’s just a 20-minute walk after meals. Strength training is especially powerful for improving insulin sensitivity.
3. Sleep at least 7–8 hours per night. Prioritize good sleep hygiene.
4. Manage stress through mindfulness, deep breathing, nature time, or anything that helps you relax.
5. Stay hydrated. Water supports kidney function and glucose regulation.
6. Track your blood sugar if you can. A CGM (continuous glucose monitor) or finger-prick test can help you learn how your body responds to different foods and habits.
7. Talk to your doctor about additional lab tests (like fasting insulin, CRP, ferritin, or fructosamine) for a more complete metabolic picture.

Final Thoughts

A high A1C can feel alarming—but it’s not always a sign of diabetes. Often, it’s an early warning that your body is struggling to maintain stable blood sugar levels. And the earlier you catch that signal, the easier it is to turn things around.

You don’t need a diagnosis to take action. In fact, acting before you become diabetic is one of the best things you can do for your long-term health, energy, and longevity.

Your A1C is like a metabolic scorecard. If the number’s climbing, it’s your body’s way of asking for support—and giving it that support now can help you avoid bigger problems later.