Recent studies have revealed an association between hyperinsulinemia and low testosterone levels in men. This finding has been demonstrated in normal physiological conditions as well as in insulin resistant states. However, the causal nature and directionality of this relationship is not yet understood. Specifically, do lower testosterone levels cause insulin resistance resulting in hyperinsulinemia or vice versa. Because insulin resistance is an important risk factor for cardiovascular disease as well as type 2 diabetes, it is important to investigate this relationship for the implications it may have for prevention of and therapeutic interventions for these disorders.