THURSDAY, May 25, 2023 (HealthDay News) — Pre-diabetes often precedes type 2 diabetes, the form of the disease most closely linked to obesity.
A new study suggests that the timing of this transition may set the stage for dementia in later years.
Pre-diabetes refers to blood sugar or glucose levels that are higher than normal but not high enough to be defined as diabetes.
Researchers found that people who were diagnosed with type 2 diabetes before age 60 were three times more likely to develop dementia than people without diabetes. That increased risk of dementia dropped for people who developed diabetes at older ages. At age 80, for example, developing diabetes was not associated with a higher chance of dementia.
“Delaying or preventing the progression of prediabetes to diabetes may be an important way to prevent dementia,” said study co-author Michael Fang. He is an assistant professor of epidemiology at the Bloomberg School of Public Health at Johns Hopkins University in Baltimore.
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Exactly how, or even if, progression from prediabetes to type 2 diabetes affects dementia risk is not fully understood, but researchers have a theory.
Insulin resistance and high blood sugar levels are associated with diabetes and contribute to the accumulation of beta-amyloid and tau in the brain. These are hallmarks of Alzheimer’s disease, the most common form of dementia.
“Amyloid-beta and tau accumulation of amyloid can cause brain cell loss, which in turn can lead to dementia,” Fang said.
“That’s it [been] it is unclear whether prediabetes is an independent risk factor or whether people with prediabetes are simply at increased risk for diabetes,” he explained. “Our findings support the theory that pre-diabetes is important for dementia primarily because these patients are at increased risk for diabetes.”
For the study, researchers analyzed data from about 11,660 people who did not have diabetes when the research began. Of these, 20% had pre-diabetes. People underwent tests measuring cognitive or mental function throughout the study, which lasted nearly three decades.
The earlier people progressed from pre-diabetes to diabetes, the more likely they were to develop dementia, the study found. Progression to type 2 diabetes before age 60 was associated with a threefold increased risk of developing dementia. This dropped to a 73% increased risk for those who developed diabetes between ages 60 and 69 and dropped further to a 23% increased risk for those who developed diabetes between ages 70 and 79.
So does stopping the progression of prediabetes to type 2 diabetes reduce the risk of dementia?
That’s the hope, said Fang. “Policies that effectively slow the progression of pre-diabetes could have a major impact on the overall dementia burden,” he said.
Modest weight loss and participation in programs that encourage healthier lifestyles, such as the National Diabetes Prevention Program, could affect those statistics, he said.
The study was published in the May 24 issue of Diabetes.
Type 2 diabetes is a well-established risk of dementia, said Yuko Hara. She is director of prevention and aging at the Alzheimer’s Drug Discovery Foundation in New York City.
Preventing or managing diabetes is one of the most important things you can do to reduce your risk of dementia and protect your brain from cognitive decline, said Hara, who reviewed the new study.
“A healthy diet, exercise, and weight management are the first steps in diabetes prevention and control,” she said. Medications are also available to keep blood sugar levels at optimal levels, she said.
The National Diabetes Prevention Program provides a roadmap to help prevent or delay type 2 diabetes.
SOURCES: Michael Fang, PhD, assistant professor, epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore; Yuko Hara, PhD, director of prevention and aging at the Alzheimer’s Drug Discovery Foundation in New York City; DiabetesMay 24, 2023