Long-Term Diabetes Linked to Significant Cognitive Impairment

HealthDay News — Midlife diabetes may contribute to cognitive decline over time, according to a study published in the Annals of Internal Medicine.

Elizabeth Selvin, PhD, MPH, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, and colleagues followed 13,351 middle-aged adults over 20 years. They came from four states: Maryland, Minnesota, Mississippi, and North Carolina. At the start of the study — 1990 to 1992 — the study volunteers were 48 to 67 years old. The researchers evaluated the study participants’ cognitive abilities at three different visits over the years, and included data on whether the volunteers had diabetes or prediabetes, as well as their blood glucose levels at various times in the study.

The researchers measured cognitive declines on a continuum, so it’s difficult to give exact measures of the decline linked to the diabetes, Selvin told HealthDay. But, on average, a 60-year-old who has diabetes has cognitive decline on par with a healthy 65-year-old who is aging normally. The researchers also found that cognitive decline was greater for people with prediabetes compared to people with normal blood glucose levels, and people with diabetes who had an HbA1c of more than 7% had an even greater risk. The researchers also noted that people who had diabetes for a longer time had more significant cognitive impairment later in life.

“What we saw was, people with prediabetes, diabetes, and poorly controlled diabetes had the higher risks of cognitive decline. The people with the worse cognitive decline were those with poorly controlled diabetes,” Selvin said.


  1. Rawlings AM et al. Ann Intern Med. 2014; doi:10.7326/M14-0737.