Abstract Background Recent randomized, placebo-controlled trial in patients with type 2 diabetes demonstrated that the sodium-glucose cotransporter 2 inhibitors reduced mortality, cardiovascular events and hospitalization for heart failure. However, those trials were not specialized design to investigate the effect of sodium-glucose cotransporter 2 inhibitors in patients with heart failure, in particular with heart failure with preserved ejection fraction. Purpose The aim of this study was to evaluate the drug efficacy of luseogliflozin, a sodium-glucose cotransporter 2 inhibitor, compared with voglibose, an alpha-glucosidase inhibitor, using brain natriuretic peptide (BNP) in type 2 diabetes patients with heart failure with preserved ejection fraction. Methods This study was a prospective, multicenter, open-label, randomized-controlled trial, comparing luseogliflozin 2.5 mg once daily or voglibose 0.2 mg three times daily in patients with type 2 diabetes suffering from heart failure with preserved ejection fraction (left ventricular ejection fraction >45% and BNP ≥35 pg/ml2) in a 1:1 randomization fashion. Randomization was undertaken using a computer-generated random sequence web response system. The primary outcome was the difference from baseline in BNP after 12 weeks of treatment between two drugs. The key secondary outcomes were the change from baseline in left ventricular ejection fraction and E/e' in echocardiographic parameters, body weight, glycohemoglobin level after 12 weeks of treatment. The safety outcomes included the incidence of major adverse cardiovascular events, hypoglycemic adverse events, and urinary tract infection. Results Between December 2015 and September 2018, 173 patients from 16 hospitals and clinics have been included in this study. Of those, 83 patients were assigned to receive luseogliflozin and 82 to receive voglibose. There was no significant difference in the reduction in the BNP concentration after 12 weeks from baseline between the two groups; the ratio of the average values at week 12 to the baseline value was 0.91 in the luseoglifllzin group as compared with 0.98 in the voglibose group (percent change, −9.0% vs. −1.9%, ratio of change with luseogliflozin vs. voglibose, 0.93; 95% confidence interval, 0.78 to 1.10; p=0.26). The key secondary outcomes including left ventricular ejection fraction, E/e', body weight, glycohemoglobin level and the safety outcomes did not differ significantly between the two groups. Conclusions In type 2 diabetes patients with heart failure with preserved ejection fraction, the administration of luseogliflozin did not lead to a significant reduction in the BNP concentration than that of voglibose. Left ventricular ejection fraction, E/e', body weight and glycohemoglobin level after 12 weeks of treatment, comparing with at baseline did not differ significantly between the two groups. (UMIN Clinical Trial Registry number, UMINehz748.005618395) Acknowledgement/Funding Novartis