Long‐term safety and efficacy of tofogliflozin as add‐on to insulin in patients with type 2 diabetes: Results from a 52‐week, multicentre, randomized, double‐blind, open‐label extension, Phase 4 study in Japan (J‐STEP/INS)

Aims To evaluate the long‐term safety and efficacy of tofogliflozin as an add‐on treatment to insulin over 52 weeks. Materials and methods This 52‐week, multicentre, Phase 4 study consisted of a 16‐week, randomized, double‐blind, placebo‐controlled phase and a 36‐week open label extension phase (NCT02201004). Japanese patients with type 2 diabetes mellitus, aged 20 to 75 years, with suboptimal glycaemic control (7.5%‐10.5%) receiving insulin monotherapy (basal‐bolus, bolus, premix [low and high] and basal) or receiving combination therapy with basal insulin and dipeptidyl peptidase‐4 inhibitor were eligible for participation. Patients who received tofogliflozin throughout the study (52 weeks) were referred to as the ‘tofo‐tofo group’ and patients who received placebo and tofogliflozin (36 weeks) were referred to as the ‘pla‐tofo group’. Results A total of 210 patients received treatment per randomization. Hypoglycaemia was the most common treatment‐emergent adverse event (AE) (42.9% in the tofo‐tofo group and 29.4% in the pla‐tofo group). Patients reported genital infection, urinary tract infection, excessive urination and AEs related to volume depletion (2.1%, 2.1%, 7.1% and 10.0% of patients in the tofo‐tofo group, and 0%, 1.5%, 2.9% and 7.4% of patients in the pla‐tofo group, respectively). Mean HbA1c and body weight at baseline (mean changes ± standard error from baseline to Week 52) in the tofo‐tofo and pla‐tofo groups were 8.53% (−0.76% ± 0.077) and 8.40% (−0.73% ± 0.102); 68.84 kg (−1.52 kg ± 0.207) and 72.24 kg (−2.13 kg ± 0.313), respectively. Conclusions This study demonstrates the safety and efficacy of tofogliflozin as add‐on to insulin therapy in type 2 diabetes mellitus patients, offering a new therapeutic solution to diabetes management.