Lower Blood Glucose Levels May Stop Cognitive Decline

Lowering blood sugar levels is a promising strategy for preventing memory problems and cognitive decline as persons age, even for those whose blood sugar levels fall within the normal range, according to the results of a new study.

“High fasting glucose levels should be avoided throughout all stages of life,” lead author Agnes Flel, MD, of Charit University Medicine in Berlin, told ConsultantLive.

“Lowering chronically elevated blood sugar levels might be a preventive strategy to protect the structure of important learning-relevant brain areas, such as the hippocampus,” Dr Flel said. “Chronically higher blood sugar levels may damage hippocampal cell membranes and disturb signaling within these cells. Additionally, this could lead to micro- and macroangiopathy of brain vessels, but also of other vessels throughout the body.”

Dr Flel and colleagues conducted a study of 141 persons, median age 63 years, who did not have diabetes mellitus or impaired glucose tolerance. Those who were overweight, drank more than 3 ½ servings of alcohol per day, or had memory and thinking impairment were not included in the study.

The participants’ memory skills were tested, along with their blood sugar levels. They also underwent brain scans to measure the size of the hippocampus area of the brain because it plays an important role in memory.

Those with lower blood sugar levels had better scores on the memory tests. On a test in which participants needed to recall a list of 15 words 30 minutes after hearing them, recalling fewer words was associated with higher blood sugar levels. For example, an increase of about 7 mmol/mol of glycated hemoglobin (HbA1c) went along with recalling 2 fewer words. Persons with higher blood sugar levels also had smaller volumes in the hippocampus.

Lowering blood sugar levels over extended periods may beneficially affect memory functions via several routes, said Dr Flel. “On one hand, functioning of brain areas like the hippocampus might improve and maintain the information transfer between cells, which is indispensable for memory encoding, storage, and retrieval,” she said.

She added, “Lowering elevated blood sugar levels may lead to a decreased damage of small and large vessels in the brain. This would have a protective effect on blood and nutrient flow within the whole brain and specifically within memory-relevant brain structures.”

In general, Dr Flel suggests following several lifestyle choices to lower blood sugar levels for both young and old patients. “These recommendations include avoidance of obesity, particularly in midlife, consuming a diet rich in fibers, vegetables, fruit, fish, and whole-grain products-the so-called ‘Mediterranean foods’-and undertaking physical activity on a regular basis,” she said.

She added, “Individuals at risk, that is, those presenting with obesity and everyone from age 55 onwards, should have regular health checks by a primary care physician that include fasting glucose and HbA1c levels for early detection and treatment of elevated glucose levels.”

The researchers published their results online on October 23, 2013 in Neurology.