In recent years, there were gradually more patients suffering from Alzheimer’s disease (AD) year by year. However, due to its unclear pathogenetic mechanism, no effective therapeutic regimens are available on relieving the symptoms or altering its course. Epidemiological data show that with the progression of aging society, diabetes mellitus is closely associated with AD incidence. Meanwhile, evidence shows that insulin treatments were effective to prevent or alleviate the symptoms of AD, which may provide a new therapeutic strategy for future AD treatment. This article reviewed the correlation between diabetes and AD and the effect of insulin on AD.