The human body is co-habituated with trillions of microbes, which are actively interacting with the human immune system. Our previous study demonstrated that a subset of individuals, characterized by a chronic absence of serum Interleukin (IL)-17 and IL-22, is more likely to be resistant to insulin compared with individuals with detectable serum IL-17/IL-22. Additional analysis pointed out that such an absence of IL-17 and IL-22 is associated with the low abundance of the gut microbiome that belongs to the class of Clostridia.