Cost-of-illness study of diabetes mellitus: focus on patients with type 2 diabetes

Objective: The aim of the study was to assess the cost of management of diabetic patients; moreover, for type 2 not insulin-dependent patients, also the durability of treatments was evaluated, in order to assess whether the switch to another therapy correlates with an increase in the costs of the diabetic disease. Methods: In the study were enrolled diabetic patients followed at the Local Health Unit (LHU) of Treviso who were on treatment with antidiabetic drugs. For each diabetic patient, costs of drug prescriptions, hospital discharge records, prescriptions for laboratory tests and medical visits, diabetic patient-supplied medical devices, and visits to emergency departments were derived from the administrative database of the LHU of Treviso and analyzed. Results: The analysis showed that hospitalization is the major cost-driver for type 2 diabetic patients, both insulin-dependent (ID) and not insulin-dependent (NID): (SIC)1,079.20 and (SIC)335.57/patient/year, respectively, accounting for 51% and 57% of the total cost. Regardless the type of diabetes (1 or 2), ID patients were most expensive given the total cost due to their pathology ((SIC)1,740.19 and (SIC)2,135.46 for type 1 and type 2 ID, respectively, vs. (SIC)588.02 for type 2 NID). Moreover, maintenance of a non-insulin therapy was shown to be the cheapest treatment. The add-on treatment metformin + DPP-4, in particular, presented the longest durability (375 +/- 51 days) compared with the other add-on therapies analyzed (256 +/- 51 days for metformin + GLP1-RA, and 311 +/- 32 days for metformin + SU/repaglinide). Conclusions: The diabetic disease accounts for about 3% of the LHU of Treviso annual budget. The highest cost is associated with ID therapy; a greater durability of non-insulin treatment would indicate a better glycemic control for NID patients, leading to savings for the Italian National Healthcare System.