A Type 2 Diabetes Diagnosis Before Age 60 Might Increase Dementia Risk By 300%, New Study Finds

Rates of diabetes are expected to jump 54% between 2015 and 2030, according to estimates published February 2017 in the journal Population Health Management—far outpacing population growth. So while there is certainly a genetic component involved in both type 1 and type 2 diabetes, science stands behind the fact that lifestyle factors can play a role in our risk for type 2 diabetes, and its precursor prediabetes.

In case you missed it, 11.3% of Americans currently have type 2 diabetes, and 1 in 3 adults have prediabetes, the National Institutes of Health reports. More and more young people are also being diagnosed with these conditions. And while we know that chronic elevated blood sugar has been linked to increased risk for cognitive decline, we haven't been quite sure the size of this impact … until now.

Individuals who are diagnosed with type 2 diabetes before age 60—meaning their prediabetes evolved—may be three times more likely to develop dementia later in life, compared to their peers without diabetes, according to a new study published May 24, 2023, in the journal Diabetologia.

What This Diabetes Study Found

As a quick refresher, prediabetes means that your blood sugar levels are higher than normal, but not high enough for you to be diagnosed with type 2 diabetes. With a multifaceted treatment plan in place at the prediabetes state, many cases can go into remission. If you have been diagnosed with prediabetes, the American Diabetes Association confirms that a healthy lifestyle could cut your risk of developing type 2 in half. But once blood sugar levels get to type 2 diabetes diagnosis territory, it's even more challenging to reverse—and comes with a whole host of health ripple effects, including higher risk for heart disease, vision loss, kidney disease and dementia, the CDC confirms.

For this new study, scientists wanted to learn more about how age at type 2 diagnosis might affect the chronic disease risk related to the condition. The researchers analyzed data from 11,656 people who did not have type 2 at the beginning of the study. About 20% (or 2,330) had prediabetes at the outset. Each participant had cognitive tests during the three-decade-long study, and they reported any doctor diagnoses of an A1C (average blood sugar over the last 3 months) over 6.5%, a level which the ADA classifies as type 2 diabetes.

The earlier in life that individuals shifted from prediabetes to type 2 territory, the higher their risk for dementia, the scientists discovered. And the impact wasn't small. Compared to their peers without elevated blood sugar, those who were diagnosed with type 2 before age 60 appeared to have triple the risk of receiving a dementia diagnosis later in life.

In terms of cognitive collateral damage, the later the type 2 diagnosis, the better. Instead of 300% increased risk, those who were diagnosed between age 60 and 69 had 73% increased risk, and people with a type 2 diagnosis between 70 and 79 were at 23% higher risk for dementia than people without diabetes. By age 80, there was no noticeable increase in dementia risk among the participants with diabetes or not.

"Prediabetes is associated with dementia risk, but this risk is explained by the development of diabetes. Diabetes onset at an early age is most strongly related to dementia. Preventing or delaying the progression of prediabetes to diabetes will substantially reduce the future burden of dementia," the study authors tell Diabetologia News.

The hope is that preventing progression of prediabetes to type 2 diabetes may lower dementia risk, but it's too early to say if that's the case. More research is required to fully flesh out how progression from prediabetes to type 2 diabetes alters dementia risk, and to determine if prediabetes itself is also a risk factor for dementia.

As for why the link between type 2 and cognitive decline appears to be significant, the study authors note that insulin resistance and high blood sugar levels are correlated with buildup of beta-amyloid and tau in the brain. These proteins seem to trigger the loss of brain cells, and excess beta-amyloid and tau has been shown to accumulate in the brains of those with Alzheimer's disease, which is the most common form of dementia.

The Bottom Line

A new health study found that those who are diagnosed with type 2 diabetes before age 60 may be at three times higher risk for dementia. No type 2 diagnosis is the best bet for your brain, but a later-in-life diagnosis may have less of a drastic impact on cognitive health.

As we continue to learn more, keep in mind that small lifestyle changes can make a big difference. Check out 7 sneaky lifestyle habits that could increase your dementia risk and 6 things you should do every day if you have prediabetes.