Can Your A1C Be Too Low?

José says it’s not unusual or unhealthy for people without diabetes to have an A1C in the 4 percent range, but in people with diabetes, “an A1C below 5.7 percent suggests extremely tight blood sugar management, which could mean you’re experiencing hypoglycemia.”

A low A1C could be a sign of other health issues, including:

• Excessive alcohol use

  [7]

• Eating disorders, such as a restrictive diet or fasting

  [8]

• Overaggressive use of insulin

  [9]

The primary concern with low A1C is the risk of dangerous low blood sugar levels, or hypoglycemia. José says this risk is usually only significant for people with diabetes who use glucose-lowering medications with a known risk of hypoglycemia, particularly insulin, sulfonylureas, and meglitinides.

“If you take insulin and you dip below 70 millgrams per deciliter (mg/dL) on a daily basis, or you’re managing your insulin and blood sugar obsessively to stay below 100 mg/dL, I would be concerned.”

“If your A1C is very low due to frequent hypoglycemia, it can permanently affect brain health and your overall daily safety,” says José.

Your A1C is largely a reflection of your lifestyle habits and the accuracy of your insulin doses if you take them, says Jones.

Chris Szoke, NP, CDCES, a nurse practitioner and diabetes specialist based in Tucson, Arizona, says that if you have diabetes and experience regular low blood sugar, you need to check in with your healthcare providers. “This is a clear sign that your insulin doses aren’t meeting your body’s needs. You need to work with your team to adjust them.”

Szoke recommends starting by testing your blood sugar more often. “If you have diabetes or you’re concerned about your A1C, your doctor can help you get a glucose meter or a continuous glucose monitor (CGM) to look more closely at your blood sugar levels.”

And Szoke says that older people with diabetes may experience some hypoglycemia unawareness after decades with the disease.

“That means it simply isn’t safe for them to aim for tight blood sugar levels and a target range between 70 and 140 mg/dL,” he says. “Instead, they may need to aim a bit higher for their daily safety, and this will correlate with a higher A1C level, too, closer to 8 percent instead of below 7.”

People with heart disease and chronic kidney disease are also at particularly high risk if they develop hypoglycemia, and they may need to set higher glycemic targets, too.

It’s important to consult with your endocrinologist or doctor to decide what your own blood sugar targets should be, and how careful you need to be about the risk of hypoglycemia.

Very rarely, dangerously low blood sugars are caused by tumors in the pancreas that produce insulin or other even less common tumors elsewhere in the body that make insulin-like substances.

• For most people with or without diabetes, a low A1C is a sign of good metabolic health.
• People with diabetes who use glucose-lowering medications, particularly insulin, need to be careful when targeting a lower A1C because of the risk of low blood sugar (hypoglycemia).
• A low A1C could also be a result of other unhealthy behaviors, such as alcohol abuse or an eating disorder.
• If you use insulin to manage your diabetes, work closely with your healthcare team to develop dosing practices that keep your blood sugar in a healthy range with a low risk of hypoglycemia.