Changes in A1C May Be Related to Heart Disease

By Lydia Davis 

Emerging evidence shows that variability in your A1C level may put you at a higher risk of stroke and heart disease. 

A recent study revealed that variability in an individual’s A1C levels could be associated with their risk for developing diabetes-related complications, such as heart disease. 

The study looked at the electronic health record data of almost 30,000 people with type 2 diabetes from 2013 to 2018 in southeast Louisiana. It included people who had at least four A1C measurements within two years of their diabetes diagnosis and no heart-related complications within that two-year period or the year before diagnosis. The sample’s demographics were 59% white and 41% African American.

What were the results?

The study determined several key findings:

• During a follow-up period of about four years, 3,746 participants (13%) developed heart disease. 

• During a follow-up period of about three and a half years, 2,348 participants (8%) developed coronary heart disease. 

• During a follow-up period of about four years, 1,851 participants (6%) had a stroke.

The researchers found an association between greater variability (the more A1C values changed over time) and a greater risk of heart complications. The researchers believe that more incidents of severe hypoglycemia (severe low blood sugar, usually below 54 mg/dL) may help explain the relationship between A1C variability and risk of heart disease, though this is not known for certain. 

It's important to note that there are many other factors that may also contribute to A1C variability, including high overall glucose levels, diabetes medications, and a person’s physical characteristics. The research team found that A1C variability and heart disease were less associated among people who were taking medications with cardio-protective benefits, such as GLP-1 agonists or SGLT-2 inhibitors. 

What does this mean?

This study leaves us with some key takeaways:

• Reducing swings in your A1C may help prevent heart disease. A good goal is to try to decrease your A1C to the target you have set with your healthcare team, or if you are at target, do your best to avoid major fluctuations over time.

• Consider treatment options that protect the heart and help you maintain stable A1C levels. GLP-1 agonist and SGLT-2 inhibitor medications are recommended for people with type 2 diabetes to increase Time in Range (TIR), reduce A1C, and lower the risk of many specific heart-related outcomes.

• A single A1C value shows a two- to three-month average of your blood glucose levels. Continuous glucose monitoring (CGM), on the other hand, provides a more complete picture of how your glucose levels change on a daily basis – and can help you focus on how to reduce low glucose levels. This may be especially helpful if you are on insulin or another glucose-lower medication like sulfonylureas (SFUs), which can put you at risk of severe hypoglycemia. Talk with your healthcare professional if you are interested in trying CGM.

What were the study’s limitations?

The study had several limitations. For example, it lacked certain demographic data about the participants including their education level, duration of diabetes, and family income. It also lacked information on risk factors, such as family history of diabetes and other chronic diseases, as well as dietary and exercise habits. Finally, since the study was conducted by looking at the electronic health record data of a specific group of people from southeast Louisiana, the conclusions may not be applicable to a broader population. 

This article is part of a series on time in range. 

The diaTribe Foundation, in concert with the Time in Range Coalition, is committed to helping people with diabetes and their caregivers understand time in range to maximize patients’ health. Learn more about the Time in Range Coalition here.