Acute Effect of Intra-nasal Insulin on Food Intake Among Middle-Aged African American Adults: the FIINAAL Study

Context 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. Objective 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. Method 39 participants received intranasal doses of Novolin-R (40IU) and a saline placebo on separate days in a double-blind, counterbalanced, crossover design, with three-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. Results 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. Conclusion 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. Research reported in this publication was partially supported by a pilot grant to Owen Carmichael from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number P30DK072476. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. It was also supported by grant U54 GM104940 from the National Institute of General Medical Sciences, which funds the Louisiana Clinical and Translational Science Center.