- A recent study examined the relationship between glucose levels, insulin, and brain health.
- Researchers found an association between higher post-meal glucose levels and an increased risk of Alzheimer’s disease.
- Further research is now required to replicate these results in a broader population.
Blood sugar spikes, also known as glucose spikes, are when the amount of glucose in a person’s blood rises sharply.
Spikes typically occur after eating particular foods, such as those containing simple carbohydrates or added sugars. They can also arise due to other factors like stress and exercise.
While people may tend to associate blood sugar spikes with diabetes and metabolism, a growing amount of research has examined the relationship between glucose responses and other areas of health.
“This finding could help shape future prevention strategies,” said Andrew Mason, PhD, one of the researchers from the University of Liverpool in the U.K., in a press release. It highlights “the importance of managing blood sugar not just overall, but specifically after meals,” Mason added.
For the study, the researchers analyzed data on a total of 357,883 people whose details are contained within the UK Biobank. The UK Biobank is a prospective study that recruited over 500,000 participants aged 40–69 between 2006 and 2010.
One of the key aspects of the current study is that the researchers did not look at specific blood sugar measurements. Instead, they looked for specific genes associated with higher glucose levels after eating.
The benefit of this approach, known as Mendelian randomization, is that focusing on genetics means that other factors such as a person’s environment or health status will not influence the results.
The study looked at people with genetic variants associated the following:
• blood sugar levels 2 hours after eating • blood sugar levels when fasting • insulin resistance • insulin levels when fasting.There was no relationship between Alzheimer’s disease and fasting blood sugar, fasting insulin, or insulin resistance.
However, the researchers found that people with genes related to higher blood sugar after eating were also 69% more likely to develop Alzheimer’s.
“The genes linked to bigger post-meal glucose spikes appear in around 40% of the population on average,” Mason explained to Medical News Today. “Their effects may indeed manifest in real life in people who tend to have higher peaks after carbohydrates and/or a slower return to baseline after eating.
“That can absolutely contribute to why one person might see a bigger glucose rise from the same food than someone else, because these variants influence glucose handling pathways such as insulin sensitivity and the timing/strength of insulin release.”
– Andrew Mason, PhD
The researchers also looked at magnetic resonance imaging (MRI) brain scans to see if there were any visible physical changes associated with different blood sugar traits.
Alzheimer’s disease and other forms of dementia are typically marked by changes or damage to certain parts of the brain that appear on MRI scans.
However, the scans in this case did not show any association between expected blood sugar levels before or after eating and brain changes.
As a result, the study authors note that the underlying mechanism behind the apparent blood sugar and Alzheimer’s relationship may not occur through a loss of brain cells and their connections.
Checking for an association between blood sugar spikes and the pathological markers of Alzheimer’s disease would be a potential next step for finding out what mechanism might be at work here, they suggest.
Further work is also needed to make sure that this finding is not just a one-off, which the authors acknowledge. Attempts to replicate the finding with another genetic dataset were unsuccessful.
Nasri Fatih, PhD, one of the study’s authors, told MNT that the two datasets defined Alzheimer’s in different ways, which could change whether or not a link showed up.
The second dataset labelled some people as Alzheimer’s cases if they reported a parent having dementia. “With a potentially noisy outcome like this, real effects can look smaller or disappear,” Fatih explained.
There are limitations with the UK Biobank dataset, too. The participants here “tend to be healthier, better educated, and more health-conscious than the general population,” the authors write in their paper.
Within this group, the researchers also only looked at data from white British participants due to low numbers of people with dementia from other demographic groups. Follow-up studies will need to reproduce these findings among a more diverse range of people.
“We first need to replicate these results in other populations and ancestries to confirm the link and better understand the underlying biology,” said Vicky Garfield, PhD, another of the study’s authors from the University of Liverpool, in the press release.
With older Black Americans twice as likely as older white Americans to develop Alzheimer’s disease or other forms of dementia, this will be an important limitation to overcome to help improve health provisions in the future.
MNT reached out to Sarah Koenck, MS, RD, a medical affairs specialist at Lingo, who had no involvement with the study.
“While more research is needed, it can’t hurt to focus on practices that support more stable post‑meal glucose responses,” Koenck told us.
She further advised that:
“Adding protein or fiber to meals, choosing more whole foods and less refined grains and starches, and incorporating movement after eating are strategies we already know can improve post-meal glucose and overall metabolic health.”
