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Diabetes Care. 2014;37(3):751-9. doi: 10.2337/dc13-1672. Epub 2013 Oct 7.

Enhancement of vasoreactivity and cognition by intranasal insulin in type 2 diabetes.

Author information

1
Corresponding author: Vera Novak, vnovak@bidmc.harvard.edu.

Abstract

OBJECTIVE:

To determine acute effects of intranasal insulin on regional cerebral perfusion and cognition in older adults with type 2 diabetes mellitus (DM).

RESEARCH DESIGN AND METHODS:

This was a proof-of-concept, randomized, double-blind, placebo-controlled intervention evaluating the effects of a single 40-IU dose of insulin or saline on vasoreactivity and cognition in 15 DM and 14 control subjects. Measurements included regional perfusion, vasodilatation to hypercapnia with 3-Tesla MRI, and neuropsychological evaluation.

RESULTS:

Intranasal insulin administration was well tolerated and did not affect systemic glucose levels. No serious adverse events were reported. Across all subjects, intranasal insulin improved visuospatial memory (P ≤ 0.05). In the DM group, an increase of perfusion after insulin administration was greater in the insular cortex compared with the control group (P = 0.0003). Cognitive performance after insulin administration was related to regional vasoreactivity. Improvements of visuospatial memory after insulin administration in the DM group (R(2)adjusted = 0.44, P = 0.0098) and in the verbal fluency test in the control group (R(2)adjusted = 0.64, P = 0.0087) were correlated with vasodilatation in the middle cerebral artery territory.

CONCLUSIONS:

Intranasal insulin administration appears safe, does not affect systemic glucose control, and may provide acute improvements of cognitive function in patients with type 2 DM, potentially through vasoreactivity mechanisms. Intranasal insulin-induced changes in cognitive function may be related to vasodilatation in the anterior brain regions, such as insular cortex that regulates attention-related task performance. Larger studies are warranted to identify long-term effects and predictors of positive cognitive response to intranasal insulin therapy.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01206322.

PMID:
24101698
PMCID:
PMC3931384
DOI:
10.2337/dc13-1672
[Indexed for MEDLINE]
Free PMC Article
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