Treatment of diabetic complications consumes health care resources. Intensive therapy was shown by the Diabetes Control and Complications Trial (DCCT) to avert complications. Economic analyses and models have been used to evaluate the cost-effectiveness of intensive therapy for people with type 1 and type 2 diabetes. An economic analysis of the DCCT estimated the cost of intensive therapy to be two to three times greater than that of conventional therapy. In contrast, an economic model predicts that intensive therapy, as compared with conventional therapy, could reduce blindness from 34 to 20% or by 41%, end-stage renal disease from 24 to 7% or by 71%, and lower-extremity amputations from 7 to 4% or by 43%. Although intensive therapy is more expensive, when the costs of complications are factored in, it becomes cost-effective for treatment of type 1 diabetes. Similarly, a model to evaluate the cost-effectiveness of intensive therapy for people with type 2 diabetes found that the lifetime costs of general and diabetes-related medical care would be approximately two times greater. However, the reduction in lifetime costs of complications, which would produce substantial reductions in costs of treatment, largely offsets the difference. Intensive therapy for type 1 and type 2 diabetes may be more expensive than conventional therapy, but from an economic perspective, it is comparable in cost to pharmacological therapies for people with hypertension and hypercholesterolemia. From a health system viewpoint, intensive therapy represents a fruitful long-term financial investment.