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Dementia Risk for People Who Have Type 1 Diabetes

Oct 27, 2018
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Angela Reyes, Pharm.D. Candidate, LECOM College of Pharmacy

A1c management over longer periods shown to decrease dementia risk for type 1 diabetes.

Diabetes can cause micro- and macrovascular complications like retinopathy, neuropathy, nephropathy, stroke, and coronary artery disease. Elevated A1C is associated with more of these complications. Glycemic control has also been linked to cognition issues in people who have type 2, but not much research has done on the effect of this with people who have type 1 diabetes. There is even less research on people who have type 1 diabetes and a risk of developing age-related diseases like dementia. According to the following study, dementia is linked to elevated A1Cs in  people who have type 1 diabetes..


Using a diabetes registry from Kaiser Permanente Northern California, researchers pulled a sample of patients who were over 50 years of age and had type 1 diabetes. Those with dementia or no HbA1c levels were excluded. Dementia diagnoses were based on electronic medical records. A diagnosis code for Alzheimer’s disease, nonspecific dementia, and vascular dementia indicated patients who developed dementia. Every HbA1c that was recorded from the patients was used to place the patient in the following categories: <6%, 6-6.9%, 7–7.9%, 8–8.9%, and >9%. Patient demographics and comorbidities were examined with dementia status using chi square and t tests. Cox proportional hazards were used to estimate the association between the categories of HbA1c and risk of dementia.

A total of 3,433 patients were followed for an average of 6.3 years. Of those followed, 155 individuals developed dementia, 519 died without a diagnosis of dementia, 1,899 did not have a dementia diagnosis at end of the study, and 860 patients left the study for more than 90 days. The mean age of those who developed dementia was 64.6 years.

It was determined that dementia risk was higher in patients with a HbA1c above 8%. Those with prolonged exposure to an HbA1c at 8–8.9% or >9% were 2.51 or 2.13 times more likely to develop dementia, respectively. A prolonged HbA1c exposure at 6–6.9% and 7–7.9% were associated with 58% and 61% lower risk of dementia, respectively. In age-adjusted models, majority exposure to HbA1c <6% was associated with increased dementia risk, but in fully adjusted models there was no significant link. Dementia risk was 60% lower in those with longer exposure to a HbA1c of 6–7.9% than those with minimal time at this HbA1c.

Long-term glycemic management is critical in maintaining cognitive function. Looking at this study and previous studies shows that people who have type 1 are at an increased risk of developing dementia, but long-term blood glucose management can reduce this risk.

Practice Pearls:

  • Glycemic management  can help maintain cognitive function in people who have type 1 diabetes.
  • Age and diabetes have an impact on development of dementia, but keeping HbA1c under 7.9% for long periods of time can reduce this risk.
  • Patients who have type 1 diabetes with a long-term A1C under 7.9% can  prevent many health complications and decrease the risk of developing dementia.


Mary E. Lacy, Paola Gilsanz, AndrewJ.Karter, Charles P.Quesenberry, Mark J. Pletcher, and Rachel A. Whitmer. Long-term Glycemic Control and Dementia Risk in Type 1 Diabetes. Diabetes Care. (2018) https://doi.org/10.2337/dc18-0073