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Poor Glycemic Management Equals Risk of Dementia

Oct 6, 2018
 
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy

Poor glycemic management raises dementia risk; patients with type 1 diabetes and prolonged increased HbA1c were found to be at two-times greater risk for dementia than those with well-managed HbA1c values.

Prolonged periods of uncontrolled blood glucose may put patients with type 1 diabetes at greater risk for dementia, a new study finds. Risk of dementia has often been linked to diabetes, with people who are elderly with type 1 diabetes over 80% more likely to have the memory loss condition than those without diabetes. While this association is well-known, exactly what glycemic index may be the cause of dementia is largely unknown.

In a new study published in Diabetes Care, investigators out of California examined different levels of glycemic control in patients with type 1 diabetes to determine its effects on risk of dementia. Using the integrated health care delivery system database, Kaiser Permanente Northern California (KPNC), a cohort of individuals 50 years and older with type 1 diabetes was created. Individuals from 1996 to 2015 were included in the analysis and followed until they had been diagnosed with dementia or met additional criteria to conclude the study (study completion in 2015 or death). Mean follow-up for the study was 6.3 years.

Every HbA1c value extracted for each patient during the study period was obtained and categorized into five different groups based on values: <6%, 6-6.9%, 7-7.9%, 8-8.9%, and ³9%. From the obtained values, patients were further categorized based on whether ³50% of HbA1c values fell in one of the five HbA1c categories.

Cox proportional hazard models were used to assess the association between cumulative HbA1c values and dementia risk.

A total of 3,433 individuals with type 1 diabetes were included in the results analysis. Of these individuals, 155 had been diagnosed with dementia by the conclusion of the study and were thus analyzed with their HbA1c cumulative values. In patients with HbA1c values in the greater two categories (8-8.9% and ³9%), dementia risk was significantly higher than those who fell in the well-controlled HbA1c categories (6-6.9% and 7-7.9%). Additionally, in patients with ³75% of their HbA1c values falling into the 8-8.9% and ³9% ranges, their dementia risk was 2.13 times higher than those who only fell into those same categories <10% of the time (95% CI 1.13, 4.01). Conversely, patients with long-term exposure to lower HbA1c values (6-6.9% and 7-7.9%) showed a 58% and 61% lower risk for dementia, respectively [(HbA1c 6-6.9%, 95% CI 0.21, 0.83) and (HbA1c 7–7.9%, 95% CI 0.18, 0.83)].

Similar results were also seen for patients in which >50% of HbA1c values fell into either the higher HbA1c categories or lower categories, with the higher categories showing greater risk for dementia, and being in the lower categories showing a significantly lower risk for dementia.

Investigators note that this may be the first study to analyze the association between glycemic management and risk for dementia in patients with type 1 diabetes. Based on the compelling results of the study, investigators concluded that elevated A1C over prolonged periods of time led to a more than two-times higher risk for dementia.

Much is still unknown about the exact mechanisms that put a patient with diabetes at risk for dementia, but a strong argument can be made for maintaining glycemic control in order to further prevent the risk for developing dementia.

Practice Pearls:

  • People with type 1 diabetes and prolonged exposure to  elevated A1C levels were at more than two-times greater risk for developing dementia than those with long term exposure to well-managed glucose.
  • People with type 1 diabetes and long-term exposure to lower HbA1c values (6-6.9% and 7-7.9%) showed a significantly lower risk for dementia than those with elevated HbA1c.

Reference:

Whitmer, R., Gilsanz, P., Karter, A., Quesenberry, C., Pletcher, M., & Lacy, M. (2018). Glycemic control and risk of dementia in a large cohort of elderly patients with type 2 diabetes. Alzheimers & Dementia,41(9). doi:10.1016/j.jalz.2009.05.392

Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy