Older adults with Type 1 diabetes with prolonged HbA1c levels of at least 8% are at least twice as likely to develop dementia, a new study suggests.
According to researchers, prior research has already established the risk of developing dementia in those who have Type 1 diabetes.
However, they indicate the relationship between glycemic control and the subsequent risk of dementia in those with Type 1 diabetes is not well understood.
How Was the Study Performed?
Researchers at the University of California, San Francisco analyzed electronic medical records from 3,433 adults at least 50 years old with Type 1 diabetes and no dementia at baseline.
Records were analyzed from the Kaiser Permanente Northern California Diabetes Registry, a registry of all members with diabetes using a combination of pharmacy and laboratory information, hospitalization records and outpatient diagnoses.
Patient data from 1996 to 2015 was studied. Of the participants, the mean baseline age was 56 years. 80.1% were white and 47.1% were women.
Dementia diagnoses were identified based on EMRs, and HbA1c measurements were obtained from the Kaiser laboratory database.
Patients were ranked by HbA1c level into the following categories: less than 6%; 6% to 6.9%; 7% to 7.9%; 8% to 8.9%; and at least 9%.
Researchers used Cox proportional hazard models to estimate the association between categories of cumulative exposure to HbA1c and risk for dementia, with age used as the time scale.
The Results
After following up at about 6 years, it was found that 155 adults (4.5%) were diagnosed with dementia, with a mean age at diagnosis of 64 years.
Researchers found that dementia risk was higher for adults exposed to an HbA1c of at least 8% compared to those exposed to an HbA1c between 6% and 7.9%.
Those exposed to an HbA1c between 8% and 8.9% for at least 75% of measurements were 2.51 times more likely to develop dementia during follow-up vs. those with less than 10% of measurements in that range.
Those exposed to an HbA1c of at least 9% were about two times more likely to develop dementia during follow-up compared to those with less than 10% of measurements in the same range.
On the other hand, adults who had HbA1c between 6% and 6.9% were 58% less likely to develop dementia during follow-up. Those with HbA1c between 7% and 7.9% were 61% less likely to develop dementia vs. those with less than 10% of measurements in the same range.
Researchers conclude that among older patients with Type 1 diabetes, those with HbA1c 8–8.9% and ≥9% had increased dementia risk, while those with majority exposure to HbA1c 6–6.9% and 7–7.9% had reduced risk.
They report the current recommendations for glycemic targets for older patients with Type 1 diabetes are consistent with healthy brain aging.
The study is published in the journal, Diabetes Care.