Better glycemic control may help significantly lower the risk for dementia among individuals with type 2 diabetes, according to a new study presented at EASD 2015, the annual meeting of the European Association for the Study of Diabetes.
Researchers looked at a cohort of more than 350,000 patients (mean age, 67 years) and found that the risk for dementia was 50% higher among patients with diabetes who had an HbA1c of 10% or greater, as compared with those who had an HbA1c around guideline target levels.
“We did expect to find some association, but our study showed a strong association, which was surprising. It suggests that control of blood sugar is very important to prevent dementia, which is a devastating disease. Not only do patients with diabetes have 40% to 50% increased risk of dementia, but how their disease is managed appears to be a strong predictor of developing dementia,” said study investigator Aidin Rawshani, MD, who is with the National Diabetes Register and Institute of Medicine in Gothenburg, Sweden.
Evidence is growing that diabetes increases the risk for future decline in brain function, with previous research supporting this association. However, until recently, there have not been specific studies like this one that have analyzed how blood sugar control, as measured by glycated hemoglobin or HbA1, affects the risk for a future dementia diagnosis.
In this study, the researchers studied extensive clinical data to explore the association between HbA1c and the risk for hospitalization for dementia among patients with type 2 diabetes.
The researchers identified all patients with type 2 diabetes and no known hospitalization for dementia who were registered in the Swedish National Diabetes Registry between January 2004, and December 2012. The patients were followed until hospital admission for dementia, death or end of follow-up on Dec. 31, 2012. Computer modeling was used to calculate the link between HbA1c and dementia.
Adjustments were made for a number of variables, including age, sex, duration of diabetes, marital status, income, education, smoking status, systolic blood pressure, BMI, estimated kidney function, statin use, proteinuria levels, type of diabetes medication, atrial fibrillation, stroke and blood pressure medications.
Among the 353,214 patients, 13,159 patients were diagnosed with dementia during a mean follow-up of 4.8 years, according to the data. Risk for dementia was 50% higher among patients with high HbA1c levels vs. target guideline HbA1c levels as defined by guidelines.
In addition, the researchers found that those patients with very low HbA1c levels, defined as lower than 6%, also had an approximately 50% increased risk for dementia.
“This adds substantially to the evidence that diabetes and dementia are linked, and this has substantial implications for both health and economy since both these conditions have increased dramatically in prevalence and incidence. This is due to the unabated increase in obesity and aging of our populations,” Rawshani told Endocrinology Advisor.
“If diabetes is a causal risk factor for dementia, it means that the increase in diabetes prevalence will increase the prevalence of dementia in our society. However, our study shows that the risk of dementia among persons with diabetes can be modified by controlling risk factors, here in terms of blood sugar.”
The researchers found that after 10 years of follow-up, 40% of the patients were alive in the group who developed dementia compared with 70% in the group who did not develop dementia.
The investigators also found that statins and antihypertensive medications appeared to be protective from dementia.
Rawshani said these findings are eye-opening and further highlight the importance of tightly controlling blood sugar as a means of protecting brain health.
“Endocrinologists should appreciate cognitive decline and dementia as a condition associated with diabetes, and glycemic control might prevent cognitive decline, which adds further to the importance of glycemic control,” said Rawshani.
- Rawshani A et al. Oral Abstract 10: Glycaemic control and incidence of dementia in 363,573 patients with type 2 diabetes: an observational study. Presented at: EASD 2015; Sept. 14-18, 2015; Stockholm.