New research suggests that people with high blood sugar levels, even those who do not have diabetes, may have an increased risk for developing cognitive impairment. This is according to a study published in the journal Neurology.

Previous research has shown that people with type 2 diabetes - a disorder that causes a person's blood sugar levels to become too high - may increase the risk of dementia.

According to the Mayo Clinic, diabetes is considered a risk factor for vascular dementia as it can damage blood vessels in the brain. This form of dementia is often caused by reduced or blocked blood flow to the brain.

But researchers from Germany now say that even those without diabetes who have high blood sugar levels may be at risk for impaired memory skills.

Scanning the hippocampus

To reach their findings, the researchers analyzed 143 people with an average age of 63, who were free of diabetes or pre-diabetes (impaired glucose intolerance).

The researchers excluded those who were overweight, consumed more than 3.5 servings of alcohol per day, and those who already had memory and thinking impairments.

The participants underwent blood glucose tests and were required to carry out memory tests. One of the tests required subjects to recall a list of 15 words 30 minutes after hearing them.

The researchers also carried out scans of the participants' brains in order measure the size of the hippocampus - a region of the brain linked to memory.

Results showed that participants who had lower blood sugar levels obtained higher scores on the memory tests, compared with those who had higher blood sugar levels.

In the word recall test, the researchers found that remembering fewer words was linked to higher blood sugar levels. They break this down, stating that an increase of 7 mmol/mol of a glucose marker called HbA1c correlated with recalling two fewer words.

Explaining their findings, Agnes Flöel, of the Charité University Medicine in Berlin and study author, told Medical News Today:

"Clinically, even if your blood sugar levels are 'normal,' lower blood sugar levels are better for your brain in the long run with regard to memory functions as well as memory-relevant brain structures like the hippocampus.

Scientifically, we were able to shed further light on the mechanisms mediating these effects. DTI-based (diffusion tensor imaging) measurements demonstrated that not only volume of the hippocampus, but also microstructural integrity is lower if blood sugar levels are higher."

Long-term glucose level management

The researchers note that these findings could lead to a better understanding of the mechanisms underlying the effect of "chronically elevated glucose function and structure," and how these factors interact.

Furthermore, the researchers say their research suggests that changes in lifestyle strategies looking at improving glucose levels long-term could be a "promising strategy to prevent cognitive decline in aging."

"These findings are important because they indicate that even in healthy non-diabetic, non-impaired glucose tolerant individuals, lifestyle choices that tend to lower blood glucose levels in young and old individuals should be recommended," Dr. Flöel told Medical News Today.

"These include, for example, avoidance of obesity (particularly in mid-life), consuming a diet rich in fibers, vegetables, protein, and whole-grain products and undertaking physical activity on a regular basis."

Dr. Flöel added that individuals at risk, such as those with obesity and those over the age of 55, should have regular health checks that include the monitoring of fasting glucose and HbA1c levels for early detection and treatment of elevated glucose levels.

The researchers add that further studies are warranted to investigate whether lifestyle interventions may have a significant impact on glucose control within non-diabetic and non-impaired glucose tolerant individuals.

Medical News Today recently reported on a study that a drug commonly used for treating diabetes has entered a clinical trial testing its effectiveness on Alzheimer's disease.