The progressive cost of complications in type 2 diabetes mellitus

Background: A substantial proportion of the costs of diabetes treatment arises from treating long-term complications, particularly cardiovascular and renal disease. However, little is known about the progressive cost of these complications. Firmer knowledge would improve diabetes modeling and might increase the financial and organizational support for the prevention of diabetic complications. Methods: We analyzed 9 years of clinical data on 11 768 members of a large group-model health maintenance organization who had probable type 2 diabetes mellitus. We ascertained the presence of cardiovascular and renal complications, staged the members progression, and estimated their incremental costs by stage. Results: We found no significant differences between men and women in the prevalence or staging of complications. Per-person costs increased over baseline ($2033) by more than 50% ($1087) after initiation of cardiovascular drug therapy and/or use of a cardiologist, and by 360% ($7352) after a major cardiovascular event. Abnormal renal function increased diabetes treatment costs by 65% ($1337); advanced renal disease, by 195% ($3979); and end-stage renal disease, by 771% ($15 675). Both cardiovascular and renal diseases were more common among older subjects, but age did not affect the additional costs of these complications. Women had substantially higher medical care costs after controlling for age and presence of complications. Incremental cost estimates based solely on "labeled" events significantly underestimate true incremental cost. Conclusions: In an aggregate population, the greatest cost savings would be achieved by preventing major cardiovascular events. For individuals, the greatest savings would be achieved by preventing progression to stage 3 renal disease.