An A1C of 5.7% is not dangerous, but it is a warning sign. It sits right at the threshold where blood sugar levels shift from normal (below 5.7%) into the prediabetes range (5.7% to 6.4%). An A1C of 6.5% or higher indicates type 2 diabetes. So at 5.7%, you’re at the very beginning of prediabetes, which means your average blood sugar over the past two to three months has been slightly elevated.
The good news: this is one of the most reversible points on the blood sugar spectrum. The changes that bring an A1C of 5.7% back into normal range are well-studied and genuinely effective.
What an A1C of 5.7% Actually Means
The A1C test measures the percentage of your red blood cells that have sugar attached to them. Because red blood cells live about three months, the test captures a rolling average of your blood sugar rather than a single snapshot. A result of 5.7% means your body is starting to have trouble processing sugar efficiently, but it hasn’t crossed into the range where sustained damage typically begins.
Think of it as an early check engine light. Your blood sugar regulation isn’t broken, but it’s under strain. Insulin, the hormone that moves sugar out of your blood and into your cells, is either being produced in smaller amounts or your cells are becoming less responsive to it. At this stage, those changes are subtle enough that most people feel completely normal.
The Risk of Doing Nothing
Prediabetes is common, affecting roughly 1 in 3 American adults, and many of them never progress to type 2 diabetes. But the risk is real. Without changes to diet, activity level, or body weight, a meaningful percentage of people with prediabetes will develop type 2 diabetes within five to ten years. The higher your A1C climbs within the 5.7% to 6.4% range, the greater that risk becomes, particularly if you also carry extra weight around your midsection or have a family history of diabetes.
A1C also predicts risk beyond diabetes itself. A large study of over 600,000 Canadian adults without diabetes found that men with A1C levels in the 5.5% to 5.9% range had a 12% higher risk of cardiovascular events like heart attack and stroke compared to men with A1C below 5.5%. Interestingly, women in the same range did not show the same increase, though researchers noted that optimizing heart health at every level of blood sugar matters regardless of sex. The point is that even slightly elevated blood sugar can stress the cardiovascular system over time.
How Reliable Is the Result?
Before making any changes based on a single A1C reading, it’s worth knowing that certain conditions can push the number up or down artificially. Severe anemia, kidney failure, liver disease, blood disorders like sickle cell anemia or thalassemia, recent blood transfusions, and even early or late pregnancy can all distort results. Some medications, including opioids and certain HIV drugs, can also interfere.
A1C and fasting blood sugar tests also don’t always agree. Research published in Diabetes Care found that the two tests identify partially different groups of people. Someone might have a normal A1C but abnormal fasting glucose, or vice versa. If your A1C comes back at 5.7% and your doctor wants to confirm the picture, they may order a fasting glucose test or an oral glucose tolerance test, which measures how your body handles a sugary drink over two hours. This is especially useful because A1C alone can miss some early cases of blood sugar problems that only show up after eating.
What Actually Lowers A1C at This Stage
The Diabetes Prevention Program, one of the largest and most influential clinical trials on prediabetes, found that participants who made modest lifestyle changes reduced their risk of developing type 2 diabetes by 58% over three years. The changes were specific but achievable: losing 7% of body weight (about 14 pounds for someone weighing 200) and exercising 150 minutes per week. That’s roughly 30 minutes of brisk walking five days a week.
The weight loss piece matters more than the number on the scale might suggest. Losing 5% to 7% of your body weight reduces the fat stored in and around your liver and pancreas, both of which play central roles in blood sugar regulation. Even without hitting that target, any sustained weight loss tends to improve A1C.
Resistance training helps too. Adding two to three sessions per week of strength exercises on nonconsecutive days improves how your muscles absorb sugar from the bloodstream, independent of weight loss. You don’t need a gym membership for this. Bodyweight exercises, resistance bands, or free weights all count.
Dietary Changes That Move the Needle
You don’t need a complete dietary overhaul. The most consistent recommendation for people with prediabetes is to increase fiber intake to 25 to 30 grams per day through fruits, vegetables, and whole grains. Fiber slows the absorption of sugar into your bloodstream after meals, which reduces the spikes that drive A1C upward over time. Most Americans eat about half that amount.
Beyond fiber, reducing refined carbohydrates (white bread, sugary drinks, pastries) and replacing them with whole grains, legumes, and vegetables makes a measurable difference. You don’t have to eliminate carbs entirely. The goal is to shift toward carbohydrates that break down slowly rather than flooding your blood with sugar all at once. Pairing carbs with protein or healthy fat at meals also blunts the post-meal sugar rise.
How Quickly Can A1C Change?
Because A1C reflects your average blood sugar over roughly three months, you won’t see a meaningful change overnight. Most people who make consistent dietary and exercise changes see their A1C drop at their next test, typically repeated three to six months later. A shift from 5.7% back to 5.5% or 5.4% is realistic with sustained effort, and that small move puts you back in the normal range.
The key word is sustained. A1C responds to what you do consistently, not what you do for a week before your blood draw. This is actually an advantage of the test: it rewards steady habits rather than short-term fixes.
Who Should Pay Closer Attention
An A1C of 5.7% carries more urgency for some people than others. Research shows that A1C in the prediabetes range predicts type 2 diabetes more strongly in people with higher BMI, meaning your weight amplifies the risk that the number represents. Ethnicity also plays a role. A1C performs differently across racial and ethnic groups, and some populations develop diabetes at lower A1C levels than others.
If you have other metabolic risk factors, like high blood pressure, high triglycerides, low HDL cholesterol, or excess weight around your waist, an A1C of 5.7% fits into a larger pattern that deserves attention. In that context, the number isn’t just about diabetes prevention. It’s a signal that your metabolic health as a whole could benefit from the same lifestyle shifts that lower blood sugar: more movement, better food quality, and gradual weight loss if you’re carrying extra weight.