The insulin-sensitizing drug phenformin, in addition to its clinical utility in type II diabetes, has been reported to lower blood lipids, reduce body fat, enhance cellular immunity, and--in rodents--to increase mean lifespan and retard the development of growth of cancer. Initial studies with the insulin-sensitizing nutrient chromium picolinate indicate that it aids glucose tolerance in type II diabetes, lowers elevated LDL cholesterol, reduces body fat while increasing lean mass, and--in rats--increases median lifespan. These effects are thus analogous to those reported for phenformin; chromium picolinate should be tested to determine whether it likewise has a favorable impact on cellular immunity and cancer risk. The ability of both phenformin and chromium picolinate to increase lifespan suggests that age-related insulin resistance may play a profound role in the aging process. It may not be coincidental that caloric restriction--the best documented technique for increasing lifespan--markedly increases insulin sensitivity. Safe, appropriate measures for promoting lifelong insulin sensitivity include a low-fat diet, exercise training, and supplemental chromium picolinate.