Daily Dose: Prediabetes, Intervening Diabetes, & Subsequent Dementia Risk

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On June 5, 2023, we reported on a study published in Diabetologia that examined whether the association of prediabetes with dementia can be explained by the intervening onset of diabetes.

The study

Researchers analyzed data from the Atherosclerosis Risk in Communities (ARIC) study, which originally enrolled nearly 16 000 adults aged 45-64 years between 1987 and 1989 from 4 US counties. For the current study, data were collected from 11 656 adults (mean age 56.8 years; 55.3% women) without diabetes at baseline and who completed visit 2 of the ARIC study (1990-1992), which was the first visit where HbA_1c and cognitive function were measured.

Prediabetes was defined as HbA_1c 5.7%–6.4%. Participants without prediabetes (HbA_1c <5.7%) served as the study reference group. Incident diabetes was defined either as self-reported physician diagnosis or diabetes medication use reported by participants during in person visits or annual telephone calls. Investigators categorized age at diabetes diagnosis as <60, 60–69, 70–79, or 80–93 years.

The findings

Of the full cohort, 20% (n=2330) had prediabetes at baseline. Overall, there were 3143 participants who developed diabetes during a median 15.9 years of follow-up. Participants with prediabetes were more likely to develop diabetes compared with those without prediabetes (44.6% vs 22.5%).

A total of 2247 participants developed dementia during a median 24.7 years of follow-up. The development of dementia varied by prediabetes and incident diabetes status. For example, among participants with prediabetes, the cumulative incidence of dementia was 16.6% higher in those who developed diabetes compared to those who did not (23.9% vs 20.5%).

Before accounting for incident diabetes, researchers observed that prediabetes was significantly associated with the risk of dementia (hazard ratio [HR] 1.12, 95% CI 1.01-1.24). However, after they adjusted for incident diabetes, the associated was attenuated and nonsignificant (HR 1.05, 95% CI 0.94-1.16).

In multivariable adjusted models, adults who were diagnosed with diabetes at younger than 60 years of age had the highest risk of dementia (HR 2.92, 95% CI 2.06-4.14). Participants diagnosed with diabetes between 80-93 years of age did not have a statistically significantly elevated risk of dementia (HR 1.13, 95% CI 0.94-1.35).

Clinical implications

"Improving early detection and engagement in people with prediabetes to prevent or delay the progression to diabetes may have long-term population benefits for dementia prevention."

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