High Blood Sugar Levels Could Contribute to Alzheimer's

A study suggests that serum glucose levels that are elevated but not high enough to diagnose diabetes may indicate an elevated risk for Alzheimer’s disease.

Studies published over the last few years have found an association between diabetes and an increased risk of developing Alzheimer’s disease. In particular, PET scans have found that Alzheimer’s patients often have reduced cerebral metabolic rates for glucose in specific brain areas. In light of these findings, researchers looking for ways to prevent Alzheimer’s believe that examining elevated fasting serum glucose and factors that regulate glucose control in cognitively normal individuals who don’t have diabetes may help reveal the etiology of Alzheimer’s.

Now, a study in this vein has found a cause-and-effect relationship between elevated blood sugar levels in patients without diabetes and an increased risk of developing Alzheimer’s. The study was conducted by researchers at the University of Arizona and published in the April 23, 2013, issue of Neurology.

The researchers examined 124 patients between the ages of 47 and 68 who had a first-degree relative with Alzheimer’s. All participants had normal brain function and did not have diabetes. The participants’ brain activity was observed using PET scans, with specific attention devoted to activity related to factors involved in regulating glucose control.

The results indicated that participants with elevated fasting blood sugar levels had patterns of reduced brain metabolism similar to those of patients diagnosed with Alzheimer’s. The findings were present and similar in both non-carriers and carriers of the APOE e4 allele, which is a significant risk factor for Alzheimer’s. This suggests that serum glucose levels that are elevated but not high enough to diagnose diabetes may indicate a risk for Alzheimer’s unrelated to one’s APOE e4 status.

The researchers suggested that additional studies “consider metabolic dysfunction as a target for AD prevention trials, such as the use of intranasal insulin.” Researchers have traditionally employed retrospective, case controlled, prospective cohort studies to assess Alzheimer’s risk factors and to design effective preventive interventions. This can be very time-consuming, but the new study suggests that using PET scans can complement the traditional approach and produce results more rapidly.

Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.