The best A1C number for most people is below 5.7%, which falls in the normal range and corresponds to an estimated average blood sugar of about 117 mg/dL or lower. If you have diabetes, the target shifts: below 7% is the standard goal for most adults, though your ideal number depends on your age, health, and risk of low blood sugar episodes.
What the A1C Ranges Mean
A1C 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 your average blood sugar over that window rather than a single snapshot. The diagnostic cutoffs are straightforward:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
Each percentage point translates to a real difference in daily blood sugar. An A1C of 6% means your blood sugar averaged around 126 mg/dL over three months. At 7%, that average jumps to 154 mg/dL. At 8%, it’s roughly 183 mg/dL. The formula behind these conversions is (28.7 × A1C) minus 46.7, if you want to estimate your own number.
The Standard Target for Adults With Diabetes
The American Diabetes Association recommends an A1C below 7% for most non-pregnant adults with diabetes. At this level, average blood sugar stays around 154 mg/dL, which meaningfully reduces the risk of complications affecting the eyes, kidneys, and nerves without pushing blood sugar dangerously low.
A tighter goal of below 6.5% is sometimes appropriate if you can reach it safely, particularly if you were diagnosed recently, are younger, or don’t take medications that carry a risk of low blood sugar. The key word is “safely.” Getting to a lower number through aggressive treatment isn’t always better, and for some people it’s actively harmful.
Why Pushing Too Low Can Be Dangerous
A large clinical trial called ACCORD tested whether driving A1C below 6% in people with type 2 diabetes would prevent heart disease. It was stopped early because the intensive treatment group had a 22% higher risk of death. The treatment itself wasn’t toxic. The problem was severe low blood sugar episodes, which more than doubled in the intensive group. Severe hypoglycemia has been linked to nearly triple the risk of death from cardiovascular causes in follow-up analyses of similar trials.
A separate retrospective study found a U-shaped pattern: people with very low A1C levels (around 6.4% while on diabetes medications) had a 52% increase in mortality, while those with very high levels (around 10.5%) had a 79% increase. The lowest-risk zone sits in between. This is why guidelines don’t simply say “lower is always better.” The best A1C is one that reduces complications without creating new risks.
When a Higher Target Makes Sense
For some people, aiming for below 7% creates more problems than it solves. A less strict target of below 8% may be more appropriate if you have a limited life expectancy, a long history of diabetes with established complications, or if treatment side effects outweigh the benefits. The logic is practical: the payoff from tight blood sugar control takes years to materialize, so the calculus shifts when time horizons are shorter or when the treatment itself causes harm.
Older adults with multiple chronic conditions or frailty typically benefit from relaxed targets as well. Canadian guidelines suggest an A1C range of 7.1% to 8.5% for older people who are frail or living with dementia, especially if they take insulin or other medications that can cause low blood sugar. For those nearing end of life, routine A1C testing isn’t even recommended. The focus shifts to preventing symptoms from blood sugar that’s too high or too low, rather than chasing a number.
Targets for Children and Teens
Children and adolescents with diabetes share the same general target as adults: below 7%. For kids who use continuous glucose monitors or insulin pumps and can manage tighter control without frequent lows, a goal below 6.5% is reasonable. For children who can’t recognize or communicate symptoms of low blood sugar, or who don’t have access to advanced diabetes technology, a slightly more relaxed goal of below 7.5% may make more sense. The guiding principle is the same as for adults: the best number is the lowest one you can maintain without significant episodes of hypoglycemia or undue burden on the child and family.
A1C Targets During Pregnancy
Pregnancy raises the stakes considerably. For women with diabetes who are planning to become pregnant, the American Diabetes Association recommends getting A1C below 6.5% before conception. High blood sugar in the earliest weeks of pregnancy increases the risk of birth defects, preeclampsia, and preterm delivery.
Once pregnant, the ideal target drops further to below 6%, which corresponds to an average blood sugar of about 126 mg/dL. An A1C below 6% in the second and third trimesters carries the lowest risk of the baby being unusually large, preterm birth, and preeclampsia. If reaching that level would cause frequent low blood sugar, the goal can be relaxed to below 7%. Pregnancy is one of the few situations where very tight control has clear, near-term benefits that justify the extra effort and monitoring.
What Your A1C Number Actually Tells You
A1C is an average, and averages can hide important details. Someone with blood sugar that swings wildly between 50 and 250 mg/dL throughout the day could have the same A1C as someone whose blood sugar holds steady at 150 mg/dL. Both might register around 7%, but their daily experience and risk profiles look very different. This is why many doctors now look at A1C alongside time-in-range data from continuous glucose monitors, which shows how many hours per day your blood sugar stays in a target zone.
Certain conditions can also make A1C misleading. Anything that changes how long your red blood cells survive, like iron deficiency anemia, sickle cell trait, or recent blood transfusions, can skew the result up or down. If your A1C doesn’t match what your daily glucose readings suggest, your doctor may use alternative tests to get a clearer picture.
If you don’t have diabetes, an A1C below 5.7% is the number to maintain. If your result comes back between 5.7% and 6.4%, you’re in prediabetes territory, but that range is where lifestyle changes like regular exercise and modest weight loss have the strongest evidence for preventing progression. If you’re managing diabetes, below 7% is the starting point for most adults, adjusted up or down based on your individual situation. The “best” number is ultimately the one that protects you from long-term complications without making your daily life worse in the process.