"We found that in elderly whose insulin sensitivity was still high, the brains were larger, and they had more grey matter in regions that are important for language skills, compared with those who had diminished insulin sensitivity. We also observed that higher insulin sensitivity was associated with better scores on the language test. Our findings offer a possible explanation for why methods that improve insulin sensitivity, such as exercise, are promising strategies for counteracting cognitive aging late in life." - Christian Benedict of Uppsala University
Insulin resistance is a complex issue. Environment, genetics and other factors are involved with insulin sensitivity. However, a healthy diet, sleep, exercise and reducing stress go a long way towards keeping you sensitive to insulin.