Cost-effectiveness of intensive insulin therapy for type 2 diabetes: a 10-year follow-up of the Kumamoto study

To evaluate the cost and effectiveness of intensive insulin therapy for typ e 2 diabetes on the prevention of diabetes complications in Japan, we perfo rmed economic evaluation based on a randomized controlled trial. A total of 110 patients with type 2 diabetes were randomly assigned into two groups, a multiple insulin injection therapy (MIT) group or a conventional insulin injection therapy (CIT) group, and were followed-up for 10 years. Economic evaluation (cost-consequences analysis) was applied to evaluate both health and economic outcomes. As outcome measures for effectiveness of intensive insulin therapy, the frequency of complications, such as retinopathy, nephr opathy, neuropathy, macrovascular event, and diabetes-related death, was us ed. For estimating costs, a viewpoint of the payer (the National Health Ins urance) was adopted. Direct medical costs associated with diabetes care dur ing 10 years were calculated and evaluated. In a base case analysis, all co sts were discounted to the present value at an annual rate of 3%. Sensitivi ty analyses were carried out to assess the robustness of the results to cha nges in the values of important variables. MIT reduced the relative risk in the progression of retinopathy by 67%, photocoagulation by 77%, progressio n of nephropathy by 66%, albuminuria by 100% and clinical neuropathy by 64% , relative to CIT. Moreover, MIT prolonged the period in which patients wer e free of complications, including 2.0 years for progression of retinopathy (P < 0.0001), 0.3 years for photocoagulation (P < 0.05), 1.5 years for pro gression of nephropathy (P < 0.01) and 2.2 years for clinical neuropathy (P < 0.0001). The total cost (discounted at 3%) per patient during the 10-yea r period for each group was $30 310 and 31 525, respectively. The reduction of total costs in MIT over CIT was mainly due to reduced costs for managem ent of diabetic complications. Our results show that MIT is more beneficial than CIT in both cost and effectiveness. Therefore, MIT is recommended for the treatment of type 2 diabetic patients who require insulin therapy as e arly as possible from the perspective of both patients and health policy. ( C) 2000 Elsevier Science Ireland Ltd. All rights reserved.