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Type 2 diabetes may be linked to cognitive problems later in life. Katherine Monge/Stocksy
  • A new study from Johns Hopkins Bloomberg School of Public Health researchers in Baltimore analyzed the association between prediabetes and dementia.
  • Their findings did not show an overall association between prediabetes and dementia risk, but they did find that developing type 2 diabetes was associated with dementia.
  • Additionally, the scientists learned that the earlier someone develops type 2 diabetes can increase dementia risk.

A study published in Diabetologia shows a connection between type 2 diabetes and dementia.

While the goal of the research was initially to find whether there is an association between prediabetes and dementia, the scientists discovered that prediabetes alone is not associated with dementia.

Instead, they learned what matters the most in terms of dementia is whether someone progresses from prediabetes to type 2 diabetes and how early the development of type 2 diabetes occurs.

With this knowledge, the medical community has yet another reason to focus on encouraging people to adapt to healthier lifestyles and not only decrease the burden of type 2 diabetes on the healthcare system but also reduce the number of people who develop dementia.

The authors utilized data from the Atherosclerosis Risk in Communities (ARIC) study. The ARIC study focused on atherosclerosis, but since it tracked a lot of data (including cognitive functioning and glycated hemoglobin), the data is valuable for researchers conducting other studies.

The ARIC study is a prospective cohort study that followed participants for almost 30 years.

The researchers in the diabetes project used data from 11,656 participants ages 45 to 64 when initially recruited. None of the participants had a type 2 diabetes diagnosis when the study began, although 20% had prediabetes.

Throughout the participants’ follow-ups, some of the data the researchers from the ARIC study tracked included blood sugar, medications, medical reports, and cholesterol levels. Additionally, the researchers used questionnaires such as the Mini-Mental State Examination (MMSE) to check cognitive functioning.

The researchers from the diabetes study divided participants they included into four groups depending on when they received a type 2 diabetes diagnosis: under 60, 60 to 69, 70 to 79, and 80 to 93 years.

From there, the scientists looked at reports of when the loss of cognitive functioning occurred.

Throughout the participant follow-ups, 44.6% of those who started the study with prediabetes went on to develop type 2 diabetes. Of the participants who did not have prediabetes, 22.5% eventually received a type 2 diabetes diagnosis.

Additionally, 2,247 participants developed dementia over the years.

While the scientists thought the connection between prediabetes and dementia was the key, they instead learned that the most important connection was when someone was diagnosed with type 2 diabetes.

“The association of prediabetes and dementia was strongly attenuated and was no longer statistically significant,” write the authors.

The earlier someone was diagnosed with type 2 diabetes, the higher their chances of developing dementia became.

According to the authors, “The cumulative incidence of dementia was highest among those who developed diabetes at an earlier age.”

Participants who received a type 2 diabetes diagnosis before the age of 60 were three times more likely to develop dementia compared to the other participants. As participant age increased, the dementia risk went down.

People diagnosed with type 2 diabetes in the 60 to 69 age bracket had a 73% increased risk, and people in the 70 to 79 age bracket had only a 23% increased risk for developing dementia. People in the 80 and up age bracket did not have an increased dementia risk.

These findings demonstrate the importance of not only preventing type 2 diabetes but working to reverse the course when someone has prediabetes.

Before someone develops type 2 diabetes, they often develop prediabetes. According to the Centers for Disease Control and Prevention (CDC), “prediabetes is a serious health condition where blood sugar levels are higher than normal, but not high enough yet to be diagnosed as type 2 diabetes”

While there are no signs or symptoms associated with prediabetes, doctors can pick up on this with routine blood labs. When a person finds out they have prediabetes, they have a chance to make changes to their diet and lifestyle to hopefully revert to a healthy blood sugar level.

Prediabetes may turn into type 2 diabetes, a metabolic disorder that causes people to have high blood sugar levels since their bodies cannot process blood sugar correctly.

The CDC notes that around 37 million Americans have type 2 diabetes (roughly 10% of Americans).

People do not always have symptoms when initially developing type 2 diabetes, but when they do symptoms may include the following:

  • increased thirst
  • frequent urination
  • fatigue
  • sores that do not heal
  • tingling in feet

People with type 2 diabetes may need to begin insulin therapy to get their blood sugar under control. They can also make lifestyle changes, including changing their diets and engaging in more physical activity.

Dr. Zeeshan Afzal, a health content advisor at online pharmacy and private health check service Welzo, who was not involved in the study, spoke with Medical News Today and explained how type 2 diabetes and dementia are linked.

“The relationship between [type 2 diabetes and dementia] is complex and multifactorial. Some potential mechanisms that may contribute to this association include vascular damage, insulin resistance, chronic inflammation, and the formation of beta-amyloid plaques in the brain,” said Dr. Afzal.

Dr. Afzal noted that type 2 diabetes is “characterized by high blood sugar levels resulting from insulin resistance or insufficient insulin production” and said this could cause damage to blood vessels and nerves.

“The brain relies on a steady supply of blood and oxygen, and any disruption in blood flow can affect its function and contribute to cognitive decline,” said Dr. Afzal.

Dr. Pouya Shafipour, a board certified family and obesity medicine physician at Providence Saint John’s Health Center in Santa Monica, California, also not involved in the research, discussed the study findings and why dementia may occur with type 2 diabetes with MNT.

“Higher states of hyperglycemia in the long-term result in insulin resistance, prediabetes, and then eventually diabetes,” Dr. Shafipour said.

“This study confirms this hypothesis that has been around for a while now,” Dr. Shafipour noted.

“Most likely, this is a result of a high state of insulin resistance, causing inflammation, microvascular damage, glycation of cerebral vascular and nerves resulting in dementia,” he explained.