If you’ve had routine bloodwork lately, you might have noticed something called hemoglobin A1c (or HbA1c) on your results. For years, this test has been the gold standard for monitoring diabetes, but it’s increasingly also being used to assess metabolic health in people who don’t have diabetes. Let’s dig into what this number actually tells us and if lower is always better.
What A1c Actually Measures
Hemoglobin A1c reflects your average blood sugar levels over the past two to three months. When glucose circulates in your bloodstream, some of it sticks to hemoglobin—the oxygen-carrying protein in your red blood cells. The more glucose floating around, the more hemoglobin gets “glycated” (coated with sugar). Since red blood cells live about three months, your A1c percentage gives a rolling average of your blood sugar control. It does not capture individual spikes and dips in glucose, but it correlates reasonably well with overall glycemic exposure and is widely used to monitor diabetes control.
For non-diabetics, a normal A1c is generally considered below 5.7%. The prediabetes range sits between 5.7% and 6.4%, while 6.5% or higher on two separate tests typically indicates diabetes. Nondiabetic adults with A1c above about 6% are more likely to have impaired fasting glucose and other cardiometabolic risk factors than those with A1c around 5.2–5.3%.
These cutoffs represent points where research has shown increased risk for complications, but like most biological measurements, they exist on a spectrum rather than as hard dividing lines.
Even in non-diabetics, A1c can vary by genetics, age, ethnicity, iron levels, sleep quality, and stress—not just diet or exercise. That’s why one person may live at 5.2% with no effort, while another naturally runs 5.6%.
The Prediabetes Gray Zone
Here’s where things get interesting—and a bit complicated. Prediabetes affects roughly 98 million American adults, though most don’t know they have it. An A1c between 5.7% and 6.4% signals that your body’s relationship with glucose isn’t quite right. Maybe your cells are becoming resistant to insulin, or your pancreas isn’t producing insulin as efficiently as it once did. Prediabetes isn’t a disease so much as a metabolic warning sign. It means your body is starting to struggle with glucose regulation—often due to reduced insulin sensitivity, higher visceral fat, chronic stress, poor sleep, or genetics.
The crucial thing about prediabetes is that it’s not a benign waiting room before diabetes. Research shows that even in this intermediate range, you face elevated risks for cardiovascular disease, kidney problems, and nerve damage—though not to the same degree as someone with full-blown diabetes. It often coexists with other metabolic risk factors such as excess weight, dyslipidemia, and elevated blood pressure. A large study published in The Lancet found that people with A1c levels in the prediabetic range had a 15-20% increased risk of cardiovascular events compared to those with normal levels.
The good news? Prediabetes is often reversible. Lifestyle changes—particularly losing 5-7% of body weight through diet and exercise—can bring A1c levels back down. The Diabetes Prevention Program, a landmark study, showed that such interventions reduced the risk of developing diabetes by 58% over three years.
Should Non-Diabetics Aim Lower?
Now we arrive at the million-dollar question: if your A1c is already in the normal range (say, 5.3%), would driving it even lower—to 5.0% or 4.8%—provide additional health benefits?
The honest answer is: we don’t really know, but the evidence suggests probably not much.
Here’s what the research tells us. Population studies have found a continuous relationship between A1c levels and cardiovascular risk even within the normal range, meaning that someone with an A1c of 5.5% might have slightly higher risk than someone at 5.0%. However—and this is critical—this doesn’t necessarily mean that artificially lowering your A1c will reduce that risk. Correlation isn’t causation.
Your A1c reflects your overall metabolic health, dietary patterns, genetics, and lifestyle. Someone who naturally maintains an A1c of 5.0% because they exercise regularly, eat a balanced diet, and have favorable genetics probably has lower risk than someone at 5.5%. But that doesn’t mean the person at 5.5% should obsess over shaving off half a percentage point. Large cohort data suggest that the lowest risk band for nondiabetic adults is roughly an A1c around 5.0–5.6%; below about 5.0% the relationship between A1c and outcomes becomes more complex.
There’s a principle in medicine that “lower is better” but it often has limits. In diabetes treatment, pushing A1c too low can actually increase risks—particularly hypoglycemia (dangerously low blood sugar), which carries its own serious complications. The ACCORD trial, which studied intensive glucose lowering in people with Type 2 diabetes, had to be stopped early because the group targeting very low A1c levels had increased mortality. While this study involved diabetics using medications, it illustrates that extremely low glucose isn’t necessarily optimal.
If someone tries to force their A1c unusually low through extreme dieting, fasting, or intensive exercise, they can run into unintended effects such as fatigue and irritability, hormonal disruption, disordered eating patterns, and nutrient deficiencies. Importantly, extremely low A1c values can sometimes reflect anemia or other medical conditions, not superior health.
For non-diabetics with normal A1c levels, there’s no evidence that trying to push numbers lower through extreme dietary restriction or other interventions provides meaningful benefit. Your body is already handling glucose appropriately. The focus should be on maintaining that healthy state through sustainable lifestyle habits rather than chasing incremental improvements in a single biomarker. In practical terms, the benefit is less about the exact number (say 5.1 versus 4.8) and more about maintaining a metabolic profile that keeps A1c comfortably below the prediabetes threshold over the long term
What Actually Matters
Rather than fixating on squeezing every tenth of a point out of your A1c, the evidence supports a broader approach to metabolic health. Regular physical activity, maintaining a healthy weight, eating a diet rich in whole foods with plenty of fiber, getting adequate sleep, and managing stress all contribute to healthy glucose metabolism—and they bring countless other benefits beyond A1c.
It’s also worth noting that A1c isn’t perfect. Certain conditions—like anemia, chronic kidney disease, or hemoglobin variants—can make A1c readings inaccurate. Some people have A1c levels that don’t match what their continuous glucose monitors show, a phenomenon called “glycation gap.” A1c is a useful tool, but it’s one piece of a larger metabolic picture.
The bottom line? If your A1c is in the normal range, you’re doing well. Maintain the healthy habits that got you there rather than micromanaging the number itself. If you’re in the prediabetic range, you have a genuine opportunity to prevent diabetes through lifestyle changes, and bringing that number down has clear benefits. But for those already in the healthy zone, obsessing over fractional improvements likely won’t move the needle much on your actual health outcomes.