Insulin spray improved gait, cognitive function in patients
Insulin plays an important role in the brain, and people with prediabetes and diabetes are at increased risk of Alzheimer's disease and cognitive decline. Delivering insulin to the brain intranasally—atomized and sprayed through the nose—has been shown to improve verbal memory and has emerged as a potential treatment for cognitive decline in the elderly.

Phase 2 randomized, double-blinded trial consisted of 24 week treatment with 40 IU of intranasal insulin (INI) (Novolin® R, off-label use) or placebo (sterile saline) once daily and 24 week follow-up. Primary outcomes were cognition, normal (NW), and dual-task (DTW) walking speeds. Of 244 randomized, 223 completed baseline (51 DM-INI, 55 DM-Placebo, 58 Control-INI, 59 Control-Placebo; 109 female, 65.8±9.1; 50–85 years old); 174 completed treatment (84 DM, 90 Controls); 156 completed follow-up (69 DM).

DM-INI had faster NW (~7 cm/s; p=0.025) and DTW on-treatment (p=0.007; p=0.812 adjusted for baseline difference) than DM-Placebo. Control-INI had better executive functioning on-treatment (p=0.008) and post-treatment (p=0.007) and verbal memory post-treatment (p=0.004) than Control-Placebo. DM-INI increased cerebral blood flow in medio-prefrontal cortex (p<0.001) on MRI. Better vasoreactivity was associated with faster DTW (p<0.008). In DM-INI, plasma insulin (p=0.006) and HOMA-IR (p<0.013) decreased post-treatment. Overall INI effect demonstrated faster walking (p=0.002) and better executive function (p=0.002) and verbal memory (p=0.02) (combined DM-INI and Control-INI cohort, hemoglobin A1c-adjusted). INI was not associated with serious adverse events, hypoglycemic episodes, or weight gain.

There is evidence for positive INI effects on cognition and gait. INI-treated T2DM participants walked faster, showed increased cerebral blood flow and decreased plasma insulin, while controls improved executive functioning and verbal memory.