Study Protocol for the Pleiotropic Effects of Sodium-Glucose Cotransporter 2 Inhibitor on Organ-Specific Sympathetic Nerve Activity and Insulin Sensitivity in Participants with Type 2 Diabetes.

Introduction: Hyperinsulinemia and hyperglycemia are associated with exaggerated systemic sympathetic nerve activity (SNA) in patients with type 2 diabetes. Sodium-glucose cotransporter 2 (SGLT2) inhibitors lower insulin levels, whereas sulfonylureas increase insulin levels. We will test whether these two classes of antidiabetic agents have different effects on SNA.

Methods: The present study is an ongoing, 24-week, one-center (only Kanazawa University Hospital), open-label, randomized, parallel trial (jRCTs 041200035). Participants with type 2 diabetes with multiple atherosclerosis risk factors are randomly assigned in a 1:1 manner to receive 2.5 mg luseogliflozin or 0.5 mg glimepiride once daily. The sample size was calculated to be 14 in each group, with a significance level of 0.05 and a power of 0.80. The design required 40 evaluable study participants. Our primary endpoint will be the change in muscle SNA (MSNA). The secondary endpoints included organ-specific insulin sensitivity measured by a hyperinsulinemic-euglycemic clamp study using an artificial pancreas combined with a stable isotope-labeled glucose infusion, bioelectrical impedance analysis, and organ-specific (cardiac, renal, and hepatic) I-meta-iodobenzylguanidine (MIBG) innervation imaging.

Planned Outcomes: Study recruitment started in April 2020 and will end in June 2024, with 40 participants randomized into the two groups. The treatment follow-up of the participants is currently ongoing and is due to finish by March 2025.

Trial Registration: The study protocol has been approved by the Certified Review Board, Kanazawa University, Ishikawa, Japan, in accordance with the guidelines stipulated in the Declaration of Helsinki (CRB4180005, 2019-001). This trial is registered with the Japan Registry of Clinical Trials, jRCTs 041200035.