Acute Effect of Intranasal Insulin on Food Intake Among Middle-Aged African American Adults: The FIINAAL Study

Intranasal insulin has emerged as a promising potential treatment for cognitive decline. However, African American adults are under-represented in this research area, and unintentional weight loss is a possible detrimental side effect.

We assessed effects of acute intranasal insulin exposure on food intake and appetite-related constructs among middle-aged, obese, cognitively normal African American adults. We hypothesized that intranasal insulin would result in fewer calories consumed, greater feelings of fullness, and less hunger compared to placebo.

A total of 39 participants received intranasal doses of Novolin-R (40 IU) and a saline placebo on separate days in a double-blind, counterbalanced, crossover design, with 3-day, eucaloric, nutritionally balanced diets preceding each dose. Doses were preceded by a 4-hour fast and followed by a test lunch. Visual analog scales (VAS) were used to assess appetite immediately before and after each dose, and after each lunch. Mixed effects linear model t tests were used to compare questionnaires and lunch intake between insulin and placebo.

There were no significant differences in food intake between conditions. However, feelings of fullness were significantly greater immediately after insulin compared to placebo. In addition, the desire to consume sweet foods decreased significantly more after insulin than after placebo.

Acute intranasal insulin was associated with a reduced desire for sweet foods and with increased feelings of fullness, but not reduced food intake, among middle-aged African American adults. Eating behavior and appetite changes should be explored further as possible side effects of intranasal insulin treatment for cognitive decline in diverse populations.