Does Controlling Blood Sugar Reduce Dementia Risk for Those with Type 1 Diabetes?

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Type 1 diabetes is increasing in incidence worldwide, and this population is now living longer than ever before thanks to advances in diabetes care and technology, however it is unknown what level of blood sugar (glycemic) control is ideal for maintaining late-life brain health. The Whitmer Lab, in a paper published in Diabetes Care in August 2018, investigated the association of long-term glycemic control with dementia in older individuals with type 1 diabetes.

“Our findings suggest glycemic control is an important and potentially modifiable factor that can be targeted to reduce dementia risk among older adults with type 1 diabetes.” - Professor Rachel Whitmer, PhD

In the first study to examine long-term glycemic control and its association with incident dementia in older individuals with type 1 diabetes, Dr. Rachel Whitmer, professor in the UC Davis Department of Public Health Science and Chief of the Division of Epidemiology, Mary E. Lacy, PhD, UCSF postdoctoral scholar, and researchers at Kaiser Permanente Division of Research aim to help answer this question for a growing group. Their paper, published in the Journal, Diabetes Care on September 4, 2018 concluded that keeping blood sugars in the range recommended by the American Diabetes Association (ADA) is associated with a lower risk of dementia.

The study followed 3,433 members of a health care system with type 1 diabetes ages 50 years and older from 1996 to 2015. Using health records of repeated measures of hemoglobin A1c (a summary measure of glycemic control in the preceding 3 months), dementia diagnoses, and comorbidities, the team used statistical modeling to evaluate the association of time-varying blood glucose levels with dementia. The team adjusted for age, sex, race/ethnicity, baseline health conditions, and frequency of hemoglobin A1c (HbA1c) measurement. They found that among older adults with type 1 diabetes those with poorly controlled blood sugar had up to a 79% higher risk of developing dementia. 

Over an average follow-up of 6.3 years, patients whose HbA1c measure greater than 50% of times measured was 8–8.9% and ≥9% had 65% and 79% higher risk of dementia, respectively. By contrast, patients whose HbA1c measurements were at or between 6–6.9% and 7–7.9% less than half the times measured had a 45% lower risk of dementia.

The current ADA guidelines recommend an A1c reading of less than or around 7.0% for adults. “It is gratifying to see that the current recommendations for glycemic control in older adults with diabetes are largely consistent with the levels needed to protect the brain,” said Dr. Rachel Whitmer. She continued, “Our findings suggest glycemic control is an important and potentially modifiable factor that can be targeted to reduce dementia risk among older adults with type 1 diabetes.”

Dr. Rachel Whitmer can be reached for comment through her executive assistant M. Brooke Mello mbmello@ucdavis.edu

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