Legacy effects and the importance of early blood sugar control for diabetes

Continuous glucose monitor

The first year after diagnosis is a crucial time for patients with Type 2 diabetes. While it’s always important to maintain healthy blood sugar levels, new research shows that better control during the first year can reduce the future risk for complications, including kidney disease, eye disease, stroke, heart failure and poor circulation to the limbs.

A new study, led by Neda Laiteerapong, MD, assistant professor of medicine at the University of Chicago, analyzed health records of more than 34,000 patients to review their hemoglobin A1C (HbA1C) values in the years after their initial diagnosis. A1C is a common measure of blood sugar control; the lower the HbA1C value, the better. (National medical organizations typically say an HbA1C between 6.5 and 7 percent is a healthy target for most diabetics.)

The study, published in the journal Diabetes Care, compared early blood sugar levels to rates of complications over an average of 13 years. The researchers found that patients with HbA1C values above 6.5 percent in the first year were much more likely to develop complications later. Patients with HbA1C values over 7 percent in the first year even had an increased risk of early death.

“Treating diabetes early is important because it puts patients’ health on a trajectory for the rest of their lives,” Laiteerapong said. “It’s not that you can’t improve your blood sugar levels later, but if you don’t start early, you have to work that much harder to stay healthy.”

“Treating diabetes early is important because it puts patients’ health on a trajectory for the rest of their lives."

Long-term, high blood sugars caused by uncontrolled diabetes cause inflammation and changes at the cellular level, as the body produces less insulin and struggles to process excess glucose in the bloodstream. This disrupts the foundations of how blood vessels are formed, which can lead to circulatory issues years later — “microvascular” problems like kidney disease, eye disease and poor circulation in the limbs, or “macrovascular” problems like heart disease and stroke.

The so-called “legacy effects” of controlling blood sugar early can prevent these problems, but the delayed benefits pose a problem for physicians. Laiteerapong led another study in 2016 showing that it can be difficult to convince patients to take medications that can help them years down the road when they may not necessarily show any immediate benefits. In that study, 40 percent of patients with hypertension and diabetes said they were less likely to take a medication when told it could take up to 10 years before they would benefit from it.

Fortunately, early diagnosis may be the best opportunity to intervene.

“When you get diagnosed with diabetes it’s a life-changing moment and it could be used as an opportunity to change your health behaviors. It’s a teachable moment,” Laiteerapong said. “This study shows that the first year is probably more important than all the others, so it’s the best time to make those changes.”

Neda Laiteerapong, MD, MS

Neda Laiteerapong is a practicing general internist and researcher in the Department of Medicine at the University of Chicago. Dr. Laiteerapong’s work focuses on improving the understanding of how the quality of life in older adults with diabetes is affected by geriatric syndromes, hypoglycemia and macrovascular and microvascular complications of diabetes.

Read more about Dr. Laiteerapong