A medical professional conducts a hemoglobin A1C test on a patient.
A hemoglobin A1C test provides data on blood sugar levels from the past one to two months. Significant shifts over time can indicate greater risk of further health troubles. (For Spectrum Health Beat)

If you have Type 2 diabetes, keeping your blood sugar levels stable over time may be key to living longer.

New research finds that people who have more swings in their blood sugar levels were more than twice as likely to die early, compared to folks with more stable blood sugar management.

The study authors used a test called hemoglobin A1C to measure blood sugar.

This commonly used test provides a rough estimate of about two to three months of average blood sugar levels.

Although treatment decisions are usually individualized based on age and other factors, most people with diabetes generally aim for an A1C of 7% or lower.

Higher numbers may indicate the need to change medications or lifestyle factors.

“In addition to reaching the hemoglobin A1C goal, fluctuation of hemoglobin A1C level is also associated with adverse events of diabetes,” said study author Dr. Sheyu Li, an endocrinologist from West China Hospital at Sichuan University in Chengdu, China.

A number of factors can affect A1C levels, including how well the body’s insulin-producing cells work, body weight, lifestyle management, other illnesses and diabetes medications, according to Li, who is currently a visiting research fellow at the University of Dundee in Scotland.

The researchers calculated A1C variability in up to 21,000 patients from Scotland who had newly diagnosed Type 2 diabetes when the study began.

Any office visit where A1C levels varied by more than 0.5% was included in their calculations. The median follow-up time was just over six years, Li said.

The patients were then split into five groups based on their A1C variability over time. For example, if someone had 4 visits out of 10 with more than 0.5% variation, their A1C variability would be 40%.

Li said a change of 0.5% from visit to visit isn’t rare.

In fact, he noted that about one-third of people in the study had such a change. This could indicate improved management (when the number is going down) or it might indicate a need for a change in medication or lifestyle (when the number goes up).

When such a change occurs, Li said someone may have had a medication added to their regimen, or they may have stopped using a medication on their own.

They may have changed certain health habits, or the change may indicate a new illness.

When variability was 60% or higher, the researchers found more than double the risk of heart disease, twice the risk of stroke and three times the risk of heart failure, nerve damage and chronic kidney disease.

The researchers also found high variability was linked to a five times greater risk of a foot ulcer and a sevenfold increase in the risk of diabetic eye disease.

The risk of death was more than twice as high for people with more A1C variability.

Because the study looked at what happened in the past, it cannot show a cause-and-effect link between A1C variability and negative health outcomes. It can only show a link between these things.

Li said that means the researchers can’t say if reducing A1C variability would improve outcomes for people with Type 2 diabetes.

At this point, he said doctors need to keep a closer watch on patients with a higher variability.

Dr. Joel Zonszein is director of the Clinical Diabetes Center at Montefiore Medical Center in New York City.

He agreed that people with more glucose variability often have more health problems.

But, Zonszein said, “It’s the chicken-and-egg question. A high A1C may cause complications, but things like liver disease and heart failure can change A1C, so it’s hard to know which came first, especially in an observational, epidemiological study.”

Still, “A1C is a good marker for outcomes. People who bounce up and down usually develop more complications,” Zonszein said.

The findings were presented recently at the European Association for the Study of Diabetes meeting, in Barcelona.

Findings from meetings are typically viewed as preliminary until they’ve been published in a peer-reviewed journal.