Researchers have been investigating whether there is a link between high blood sugar and the development of Alzheimer's disease for some time. A new study may offer some sweet comfort for patients with prediabetes and high blood sugar.
A recent study looked at the blood sugar levels of a group of people when they were alive and then tested their brains for Alzheimer's after they died years later.
The results showed no link between high blood sugar and insulin levels and the development of Alzheimer's.
In this study, Madhav Thambisetty, MD, PhD, of the National Institute on Aging in Baltimore, Maryland, led a team to investigate the relationship between blood sugar levels in prediabetes and the potential for developing Alzheimer's disease.
Previous research has suggested that diabetes and prediabetes may be risk factors for developing Alzheimer’s disease — a specific type of dementia.
Also called hyperglycemia and glucose intolerance, prediabetes occurs when a person has higher than normal levels of sugar in his or her blood stream. The excess sugar can cause damage to the body’s vital organs.
The researchers used data on 197 people involved in the Baltimore Longitudinal Study of Aging. Each of the participants had his or her blood sugar tested at least twice towards the end of life. After death, autopsies were performed on the participants’ brains to check for signs of Alzheimer's.
Of these participants, 101 had dementia and 96 did not have dementia.
An additional 53 living patients were included in this study for blood sugar testing and brain scans. All of the participants were 69 years or older at the start of the blood sugar testing.
People with Alzheimer's had fasting glucose levels (blood sugar after not eating for some hours) of 100 mg/dL, compared to 98 mg/dL in people without Alzheimer's.
Insulin levels were also tested. Insulin is a hormone produced by the pancreas to remove excess sugar from the blood.
People with Alzheimer's had fasting insulin levels of 9.6 mIU/mL, compared to 9.0 mIU/mL in people without Alzheimer's.
Participants who had taken medication to help control their blood sugar scored similarly on three dementia assessment tests compared to other participants. When combined, all three tests were scored from mild to severe Alzheimer's findings on a scale from 2 to 6. On average, people on no medication scored a 3.7, people on blood sugar medication scored a 3.7 and people on insulin scored a 3.6.
The researchers concluded that symptoms of prediabetes or actual diabetes were not associated with the development of Alzheimer's among these participants.
The study authors noted that this study was done with voluntary participants who had access to high quality health care, and not a community sample.
The authors wrote that the effect of insulin on the brain is complex and not limited to Alzheimer’s-specific alterations in the brain.
This study was published in July in JAMA Neurology.
The National Institute on Aging, the Burroughs Wellcome Fund for Translational Research and the National Institutes of Health provided funding for this project. No conflicts of interest were reported.