Human ageing is associated with impaired insulin activity, which may lead to alterations in energy homeostasis and type 2 diabetes. In addition, increasing evidence suggests that type 2 diabetes-associated hyperglycemia and hyperinsulinemia may accelerate cellular senescence. On the other hand, impaired insulin signaling in animal models extends organismal lifespan and interventions that promote longevity prevent metabolic alterations and diabetes. Here, we review the mechanisms underlying the development of age-associated hyperglycemia, its impact on cellular senescence and the effect of insulin-signaling pathways on energy balance and ageing.