Type 2 diabetes, also known as adult onset diabetes, is a chronic disease impacting an estimated 34 million Americans. If led untreated, it can lead to a host of complications including blindness, heart disease and stroke. Researchers are also now finding possible connections between diabetes and increased risk for developing Alzheimers.
A recently completed British study of over 10,000 men and women, tracked the development of diabetes and dementia within the group from 1985-2019. What they learned was that the earlier the onset of of diabetes, the greater the risk of developing dementia later. Even with controlling for other risk factors for dementia, such as race, heart conditions, and physical activity, researchers found a correlation between diabetes and dementia.
The researchers observed the age at which diabetes was initially diagnosed correlated with the risk of developing dementia. For example, a 70 year old diagnosed with type 2 diabetes had an 11 percent increased risk for later developing dementia. Comparatively, those who developed diabetes younger had a much greater risk for dementia later in life: a 53 percent chance risk of later developing dementia for those diagnosed with diabetes at age 65 and a 77 percent risk of at age 60.
Up to 81 percent of people living with Alzheimer’s are estimated to have type 2 diabetes. While scientists are still investigating how diabetes is linked to dementia, it is well known that the brain uses enormous amounts of glucose. A hallmark of type 2 diabetes is associated with hyperglycemia, high blood sugar, due to insulin resistance. With insulin resistance, cells no longer respond to insulin, the hormone that regulates cellular energy and metabolism. A recent study conducted by researchers at UNLV showed that chronic hyperglycemia impairs and alters working memory networks. The study revealed the hippocampus and the anterior cingulate cortex—parts of the brain central to forming and retrieving memories—were over-communicating and, as a result causing mistakes.
Insulin resistance in the brain is another growing area of investigation. In fact, Alzheimer’s Disease is sometimes referred to as Type 3 Diabetes. By studying brain tissue from deceased Alzheimer’s patients, a team of BYU researchers discovered the genes used to break down glucose in the brain had been compromised. Insulin resistance makes it difficult for the brain to break down the glucose it needs for energy. But, the brain could potentially draw from another source of energy known as ketones, molecules the body makes when it’s burning relatively high amounts of fat and when insulin levels are low. However, the average person consuming a Western diet high in carbohydrates or insulin spiking foods, has fewer ketones available as alternative fuel for the brain. What’s promising is this line of investigation points to lifestyle and diet as a possible origin for Alzheimer’s.
Nearly 1 in 7 Americans have diabetes, a disease that’s on its own can have devastating consequences. But Type 2 diabetes can be managed and its complications reduced by monitoring blood sugar and following a personalized program of exercise, diet and medication. A growing body of evidence now supports diabetes prevention and management can also reduce risk of developing Alzheimer’s down the road.