Your A1C came back high and you want to know how worried you should be. A1C measures your average blood sugar over the past 2 to 3 months, expressed as a percentage. The higher the number, the more sugar is coating your red blood cells, and the more damage is happening to your blood vessels and organs.
So what level is actually dangerous? The short answer: any A1C above 6.5% means you have diabetes, and the risk of serious complications rises sharply above 8%. But the full picture is more nuanced than that.
A1C Ranges and What They Mean
Below 5.7%: Normal
Your blood sugar management is healthy. An A1C in this range corresponds to an average blood glucose of about 117 mg/dL or lower. No diabetes-related intervention is needed, though maintaining healthy habits remains important.
5.7% to 6.4%: Prediabetes
This is the warning zone. About 96 million American adults, more than 1 in 3, have prediabetes. At this level, your blood sugar is higher than normal but not yet in the diabetes range.
The critical fact about prediabetes: without intervention, 15 to 30% of people with prediabetes will develop type 2 diabetes within 5 years. With lifestyle changes, that progression can be prevented or significantly delayed.
6.5% to 7.0%: Diabetes (Early or Well-Controlled)
An A1C of 6.5% or higher on two separate tests confirms a diabetes diagnosis. However, an A1C of 7% or below is the target for most adults with diabetes according to the American Diabetes Association. If your A1C is in this range, your diabetes is relatively well-controlled.
7.1% to 8.0%: Above Target
Your diabetes management needs improvement. At this level, the risk of diabetic complications begins to increase meaningfully. An A1C of 8% corresponds to an average blood glucose of about 183 mg/dL.
Your healthcare provider will likely want to adjust your treatment plan, whether that means medication changes, dietary modifications, or more frequent monitoring.
8.1% to 10.0%: Poorly Controlled
This is where the danger becomes significant. An A1C above 8% is associated with substantially higher rates of diabetic complications including nerve damage, kidney disease, and vision problems. Your doctor may describe this as “uncontrolled diabetes.”
Above 10%: Severely Uncontrolled
An A1C above 10% is a medical emergency in slow motion. At this level, your average blood sugar is approximately 240 mg/dL or higher, and serious damage is actively occurring. You are at high risk for diabetic ketoacidosis, severe nerve damage, kidney failure, vision loss, and cardiovascular events.
If your A1C is above 10%, you need urgent medical attention and likely a significant change in your treatment regimen.
Complications at Each A1C Level
The landmark UKPDS study showed that each 1% reduction in A1C lowers the risk of complications:
- Microvascular complications (eye, kidney, nerve damage): Risk drops 37% for each 1% reduction in A1C
- Diabetes-related death: Risk drops 21% per 1% reduction
- Heart attack: Risk drops 14% per 1% reduction
- Stroke: Risk drops 12% per 1% reduction
This means going from an A1C of 9% to 8% reduces your risk of eye and kidney damage by over a third. Every fraction of a percent matters.
Specific Complications of High A1C
Eye Damage (Diabetic Retinopathy)
Persistently high A1C damages the tiny blood vessels in your retina. This can lead to blurred vision, floaters, and eventually blindness. Diabetic retinopathy is the leading cause of blindness in working-age adults. Annual eye exams are essential once diagnosed with diabetes.
Kidney Damage (Diabetic Nephropathy)
High blood sugar damages the filtering units of your kidneys over time. This progresses silently for years before symptoms appear. Your eGFR and urine albumin levels are the key tests for catching this early.
Nerve Damage (Diabetic Neuropathy)
The most common complication, affecting up to 50% of people with diabetes. Starts as tingling or numbness in the feet and hands. Can progress to severe pain, loss of sensation, and foot ulcers that resist healing.
Cardiovascular Disease
Diabetes doubles your risk of heart attack and stroke. High A1C accelerates the buildup of plaque in your arteries. Monitoring your heart disease risk factors alongside A1C gives you a more complete picture.
How to Lower Your A1C
Lowering your A1C is not about perfection. It is about consistent, sustainable changes. Here are the interventions with the strongest evidence:
Dietary Changes
- Reduce refined carbohydrates: White bread, white rice, sugary drinks, and pastries cause the sharpest blood sugar spikes
- Increase fiber intake: Fiber slows sugar absorption. Aim for 25 to 30 grams per day from vegetables, legumes, and whole grains
- Watch portion sizes: Even healthy carbs raise blood sugar when eaten in large quantities
- Time your meals consistently: Regular meal timing helps stabilize blood sugar throughout the day
Physical Activity
Exercise lowers blood sugar by increasing insulin sensitivity. The American Diabetes Association recommends 150 minutes of moderate-intensity activity per week. Even a 15-minute walk after meals significantly reduces post-meal blood sugar spikes.
Medication
If lifestyle changes alone are not enough, several medication classes can help:
- Metformin: First-line medication for type 2 diabetes. Reduces A1C by 1 to 1.5% on average
- GLP-1 receptor agonists (semaglutide, liraglutide): Lower A1C and promote weight loss
- SGLT2 inhibitors (empagliflozin, dapagliflozin): Lower A1C and have cardiovascular and kidney protective effects
- Insulin: When other medications are insufficient, insulin provides the most direct blood sugar control
Weight Loss
Losing just 5 to 7% of body weight can significantly improve A1C. For a 200-pound person, that is 10 to 14 pounds. Use our BMR calculator to understand your caloric needs and set realistic goals.
Frequently Asked Questions
Can A1C be wrong?
Yes. Certain conditions can give falsely high or low A1C readings: hemoglobin variants (common in sickle cell trait), iron deficiency anemia, recent blood loss or transfusion, kidney disease, and pregnancy. If your A1C does not match your home glucose readings, ask your doctor about these possibilities.
How fast can A1C drop?
Since A1C reflects a 2 to 3 month average, meaningful changes take about that long to show up. Most people see a 0.5 to 1.5% reduction in A1C within 3 months of starting or intensifying treatment. Dramatic drops of 2% or more are possible but usually require significant medication changes.
What is a safe A1C target for elderly patients?
For older adults, especially those with other health conditions, many guidelines recommend a less aggressive target of 7.5% to 8%. Overly tight blood sugar control in elderly patients increases the risk of dangerous hypoglycemia.
