Younger age at diagnosis of diabetes linked to higher risk of developing dementia

Key points to remember:

• Adults diagnosed with diabetes under age 60 have an increased risk of developing dementia.
• People diagnosed with diabetes at age 80 or older did not have a higher risk of dementia.

Adults who are diagnosed with diabetes at a younger age have an increased risk of developing dementia, but researchers found no association between prediabetes and dementia risk, according to study data published in Diabetes.

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“We believe that delaying the progression of prediabetes has the potential to have a broad public health impact,” Michael Fang, PhD, assistant scientist in epidemiology at the Johns Hopkins Bloomberg School of Public Health, Healio told. “Prediabetes affects 96 million adults in the United States and nearly 500 million adults worldwide. These numbers will continue to rise. Policies that effectively slow the progression of prediabetes can have a significant impact on the overall burden of dementia.

Fang and his colleagues analyzed data from the ARIC (Atherosclerosis Risk in Communities) study. Data were collected from 11,656 adults who made the second visit between 1990 and 1992 (mean age, 56.8 years; 55.3% female). Prediabetes was defined as an HbA1c between 5.7% and 6.4%. Incident diabetes was determined by self-reported diagnosis or diabetes medication use. Dementia was determined by expert committee review of cognitive function assessments, informant reports, and hospitalization codes. Demographics, lifestyle factors, and clinical factors were collected at baseline. Follow-up continued until first diagnosis of dementia, death, loss to follow-up, or study termination on December 31, 2019.

Of the cohort, 20% had prediabetes at baseline. There were 3,143 adults who developed diabetes during a median follow-up of 15.9 years. A higher percentage of adults with prediabetes developed diabetes than those without prediabetes (44.6% vs. 22.5%).

Of the cohort, 2,247 adults developed dementia during a median follow-up of 24.7 years. The proportion of adults who developed dementia was higher in diabetics than in non-diabetics (23.9% versus 20.5%).

After adjusting for incident diabetes and other covariates, the researchers found no association between prediabetes and dementia. In multivariate models, adults who developed diabetes under age 60 had a higher risk of dementia than those without diabetes (adjusted RR=2.92; 95% CI, 2.06-4 ,14). The risk of dementia in adults who developed diabetes between the ages of 60 and 69 (aHR=1.73; 95% CI, 1.47-2.04) and between the ages of 70 and 79 (aHR=1.23; 95% CI, 1.08-1.4) was also higher than those without diabetes. Adults who developed diabetes at age 80 or older did not have an increased risk of dementia.

Fang said the findings reveal the importance of slowing or preventing the progression from prediabetes to diabetes, especially in young adults.

“Providers can help patients slow and prevent the progression of prediabetes through modest weight loss,” Fang said. “Referring patients to lifelong structured programs can be particularly effective. The government has created a federal program called the National Diabetes Prevention Program aimed specifically at preventing diabetes nationwide. However, less than 5% of American adults with prediabetes are referred to these programs by their providers.

Fang said more research is needed to understand how to effectively implement effective diabetes prevention policies and programs.