Being diagnosed with diabetes late in life associated with higher risk of developing dementia, new study indicates

People diagnosed with Type 2 diabetes later in life had a 16 per cent higher risk of developing dementia than people without diabetes, a new study indicates.

Among seniors with Type 2 diabetes, the risk of dementia was greatest in those with existing cerebrovascular disease restricting blood flow to areas of the brain, other forms of vascular disease, kidney problems and hospitalizations for low blood sugar.

Dr. Gillian Booth, an endocrinologist at St. Michael’s Hospital and an adjunct scientist at the Institute for Clinical Evaluative Studies (ICES), compared health data on 225,000 people in Ontario between the ages of 66 and 105 who had recently been diagnosed with diabetes, and 668,000 similar patients who did not have diabetes. They were followed for five to seven years to see whether they developed dementia. The results were published online in the journal Diabetes Care.

Dr. Booth said there was a growing body of evidence to support an association between diabetes and dementia, since they share common cardiovascular and metabolic risk factors. High blood pressure, high cholesterol and obesity in mid-life have been implicated in the risk of dementia in later years. Insulin may also affect the cortex area of the brain, responsible for learning and memory.

“With the aging of the world’s population, both diabetes and dementia are expected to become global epidemics,” she said. The number of people with dementia is expected to grow from the current 44 million to 135 million by the year 2050.

The study found that cerebrovascular disease was associated with a two-fold increase in the risk of dementia, which Dr. Booth said underscored the importance of stroke prevention. She said another important observation was that the association between diabetes and dementia risk increased over time. 

“As life expectancy continues to improve for older populations with diabetes, we need to work to identify strategies that can effectively ward off dementia,” she said.

Fewer South Asians with late life diabetes developed dementia, despite being thought to have a higher risk of cardiovascular complications. Low-income was a high-risk factor for dementia, as it is for other diabetes complications.

Dr. Booth said she believed this was the first large, population-wide study to report an association between diabetes and dementia among elderly people with newly diagnosed dementia and the first of its kind in North America.

This study received funding from the Canadian Institutes of Health Information.

"Risk of dementia in seniors with newly diagnosed diabetes: a population-based study" will be published in the October issue of the journal Diabetes Care.

Author block: Nisha Nigil Haroon, Peter C. Austin, Baiju R. Shah, Jianbao Wu, Sudeep S. Gill, Gillian L. Booth.

About St. Michael’s Hospital 
St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future healthcare professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto. 

About ICES
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario

For further information please contact:

• Leslie Shepherd
• Manager, Media Strategy
• St. Michael's Hospital
• 416-864-6094 / [email protected]

• Kathleen Sandusky
• Media Advisor, ICES
• [email protected]
• (o) 416-480-4780 or (c) 416-434-7763