Economic Impact of Combining Metformin with Dipeptidyl Peptidase-4 Inhibitors in Diabetic Patients with Renal Impairment in Spanish Patients

Background: To evaluate resource use and health costs due to the combination of metformin and dipeptidyl peptidase-4 (DPP-4) inhibitors in patients with diabetes and renal impairment in routine clinical practice. Methods: An observational, retrospective study was performed. Patients aged >= 30 years treated with metformin who initiated a second oral antidiabetic treatment in 2009 to 2010 were included. Two groups of patients were analysed: metformin+DPP-4 inhibitors and other oral antidiabetics. The main measures were: compliance, persistence, metabolic control (glycosylated hemoglobin<7%) and complications (hypoglycemia, cardiovascular events) and total costs. Patients were followed up for 2 years. Results: We included 395 patients, mean age 70.2 years, 56.5% male: 135 patients received metformin+DPP-4 inhibitors and 260 patients received metformin+other oral antidiabetics. Patients receiving DPP-4 inhibitors showed better compliance (66.0% vs. 60.1%), persistence (57.6% vs. 50.0%), and metabolic control (63.9% vs. 57.3%), respectively, compared with those receiving other oral antidiabetics (P<0.05), and also had a lower rate of hypoglycemia (20.0% vs. 47.7%) and lower total costs (sic 2,486 vs. sic 3,002), P=0.001. Conclusion: Despite the limitations of the study, patients with renal impairment treated with DPP-4 inhibitors had better metabolic control, lower rates (association) of hypoglycaemia, and lower health costs for the Spanish national health system.