As you grow old, your brain may shrink, leading to problems with memory. In the past, brain shrinkage has been tied to diabetes. Now, new research suggests that brain shrinkage may start well before the onset of diabetes.
People with blood sugar levels in the high end of the normal range may have a higher risk of brain shrinkage that happens as a normal part of aging and in diseases like dementia.
Type 2 diabetes is a condition that occurs when blood sugar rises beyond normal levels. High blood sugar puts people at risk of many health problems throughout the body.
"Numerous studies have shown a link between type 2 diabetes and brain shrinkage and dementia, but we haven't known much about whether people with blood sugar on the high end of normal experience these same effects," said Nicolas Cherbuin, PhD, of Australian National University and lead author of the current study.
According to the World Health Organization, a normal blood sugar level before eating is below 110 mg/dL.
Dr. Cherbuin and colleagues found that people with normal blood sugar levels were more likely to have brain shrinkage in the hippocampus and amygdala - two areas of the brain involved in memory and other thinking processes - compared to people with lower blood sugar levels.
In their study, the researchers controlled for other factors that could be involved in brain shrinkage, including age, high blood pressure and smoking among other factors.
In other words, they made sure that these factors were not responsible for brain shrinkage in the study's participants.
After accounting for these factors, the researchers found that 6-10 percent of brain shrinkage was linked to blood sugar on the high end of normal.
The study's results suggest that blood sugar levels can affect brain health, even in people without diabetes, said Dr. Cherbuin.
While more research is needed, these findings may lead researchers to take a second look at the definitions of normal blood sugar levels and diabetes, he said.
For their study, the researchers looked at brain scans of 249 people between 60 and 64 years of age who had normal blood sugar levels.
The study was funded by the National Health and Medical Research Council Australia and the Australian Rotary Health Research Fund.
The research was published September 4 in the journal Neurology.