High HbA1c increases risks for dementia subtypes in type 2 diabetes
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Among adults with type 2 diabetes, risks for vascular and nonvascular dementias increase with HbA1c levels, but Alzheimer’s risk appears to increase only with very HbA1c, according to registry data from Sweden.
“People with diabetes used to live 10 years less than those without diabetes,” Carlos Celis-Morales, PhD, a research fellow at the Institute of Cardiovascular and Medical Sciences at the University of Glasgow, U.K., told Healio. “However, due to improvement in treatments, diabetic patients have increased their life expectancy. This means that they will also increase their risk of developing other chronic diseases strongly associated with aging, such as dementia.”
Celis-Morales presented the findings at the European Association for the Study of Diabetes virtual meeting.
Researchers analyzed data from 378,299 adults with type 2 diabetes from the Swedish National Diabetes Registry, which includes information on approximately 90% of all adults with type 2 diabetes in Sweden. This information was compared with data from 1,886,022 age- and sex-matched controls in the Swedish Total Population Registry. Researchers recorded the number of adults with Alzheimer’s disease, vascular dementia and non-vascular dementia. HbA1c levels were used from the diabetes group to evaluate the association between glycemic control and dementia.
The prevalence of dementia was 2.7% in the diabetes group and 2.5% in the control group. Adults with type 2 diabetes had a 36% greater chance for developing vascular dementia compared with the control group (HR = 1.36; 95% CI, 1.03-1.09). There was a slightly elevated risk for the diabetes group developing nonvascular dementia compared with controls (HR = 1.08; 95% CI, 1.04-1.12). For Alzheimer’s disease, adults with type 2 diabetes had a lower risk than the control group (HR = 0.92; 95% CI, 0.87-0.98).
Individuals in the diabetes group with an HbA1c of 7% (53 mmol/mol) or higher had an elevated risk for all three dementia subtypes when compared with adults with type 2 diabetes and HbA1c of 52 mmol/mol or less, with the risk climbing as HbA1c increased. Adults with an HbA1c greater than 10% (87 mmol/mol) had the greatest risk for vascular dementia (HR = 1.93; 95% CI, 1.53-2.42) and nonvascular dementia (HR = 1.67; 95% CI, 1.45-1.91).
There was also an elevated risk for Alzheimer’s disease (HR = 1.34; 95% CI, 1.03-1.75) for adults in the highest HbA1c category; however, Celis-Morales noted clear associations were not found for adults with HbA1c between 7% and 9% (53 mmol/mol and 75 mmol/mol).
“Poor glycemic control increases your risk of dementia, especially vascular dementia,” Celis-Morales said. “The risk of vascular dementia in people with diabetes is 35% higher than those without diabetes. However, if you have diabetes and you don’t have a good glucose control, then your risk will be 95% higher than those who are diabetic but who have a good glycemic control. ... Identifying diabetic patients who have a poor glycemic control and helping them to get better glycemic control could reduce risk of developing dementia.”
Although specific factors for the higher risks for dementia vary between subtypes, some of the most common were diabetes duration, BMI, existing cardiovascular diseases and hypertension, according to Celis-Morales.
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Celis-Morales C, et al. Glycated hemoglobin, type 2 diabetes and the links to dementia and its major sub types: findings from the Swedish National Diabetes Register. Presented at: European Association for the Study of Diabetes Annual Meeting; Sept. 21-25, 2020 (virtual meeting).
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