The association of obesity, insulin resistance, and chronic low-grade inflammation has been evident for several years by now. Since obesity, insulin resistance, and inflammation all are related to aging as well, the mechanisms underlying this association are of critical importance for gerontology. Although several molecular and cellular mechanisms by which inflammatory events decrease the sensitivity to insulin in obese patients have recently been elucidated, the pathogenesis of obesity-induced insulin resistance is still obscure in many aspects. This review aims at giving a general view on the known mechanisms and summarizing the recent progress. Research currently focuses on adipose tissue inflammation as predominantly driven by adipose tissue macrophages, but also related alterations in other organs (liver, muscle, pancreas) have to be considered. Moreover, novel approaches for treatment and prevention of insulin resistance and type 2 diabetes by targeting obesity-induced inflammatory processes are discussed here.