Taking insulin as a nasal spray was found to improve walking speed and cognitive function in older adults even if they didn’t have diabetes, according to a study published in the Journal of Neurology.
As noted in a press release on the study, it’s estimated that about 25% of adults ages 65 and older have type 2 diabetes. But a potentially even greater proportion of older adults has prediabetes, or elevated blood glucose levels that don’t reach the threshold for diabetes. Many people with prediabetes don’t receive much follow-up care or guidance, and some aren’t even formally diagnosed with the condition, studies have shown — making it difficult to know exactly how many people have the condition. But even if it doesn’t progress into type 2 diabetes, prediabetes is linked to serious health risks, including a higher risk for major depression and cognitive decline.
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For the latest study, researchers at Beth Israel Deaconess Medical Center in Boston looked at the long-term effects of using an intranasal insulin spray in 156 adults ages 50 to 85. Out of these participants, 51 had type 2 diabetes and 58 didn’t have diabetes. The researchers were interested in how taking insulin by nose might affect brain function, since past studies have shown that taking insulin in this manner may improve verbal memory in older adults. Brain function can also directly affect motor function, including the ability to walk, so the researchers looked at both walking speed and cognitive function as the two main areas of outcomes in the study.
Specifically the outcomes the researchers looked at were normal and dual-task (walking while doing a cognitively demanding task) walking speeds, attention, memory and executive function, and mood. This was accomplished using a variety of validated (previously studied) tests. After initial tests, participants with and without diabetes were randomly assigned, as separate groups, to take either intranasal insulin or a placebo (inactive saline nasal spray) once a day for 24 weeks. For the group that took insulin, the dose was 40 units of Novolin R.
Intranasal insulin linked to faster walking speeds, greater blood flow in frontal lobe
After 24 weeks, the researchers found that the participants with diabetes who received intranasal insulin had faster walking speeds both during and after the period of insulin treatment. They also had greater blood flow in the frontal lobe of their brain, as well as less insulin resistance and less insulin circulating in their blood — even though they were taking insulin. Among participants without diabetes, those who took insulin showed improvement in measures of decision-making and verbal memory, as noted in a press release on the study.
Overall, participants with or without diabetes who took intranasal insulin had faster walking speeds and showed better executive function and memory, with the biggest improvements in decision-making and verbal memory seen in participants with prediabetes.
The researchers concluded that this study “provides proof-of-concept for preliminary safety and efficacy and supports future evaluation of [intranasal insulin’s] role to treat [type 2 diabetes] and age-related functional decline.”
For people with prediabetes, this study shows the promise of “potential early intervention using [intranasal insulin] in this population to prevent or slow down the progression toward Alzheimer disease” and other forms of dementias, said study author Long Ngo, PhD, an associate professor of medicine and biostatistics at Harvard Medical School, in the press release — adding that this finding “deserves more attention and definitive confirmation in a larger trial.”
Want to learn more about maintaining cognitive health with diabetes? Read “Nine Tips to Keep Your Memory With Diabetes,” “Keeping Your Brain Strong With Diabetes” and “Memory Fitness: How to Get It, How to Keep It.”
Want to learn more about prediabetes? Read “What Is Prediabetes? Symptoms, Treatment, and More,” “Prediabetes Treatment” and “Diabetes Prevention: Eat to Beat Diabetes.”