Comparison Between Pioglitazone/Metformin Combination Therapy and Sitagliptin/Metformin Combination Therapy on the Efficacy in Chinese Type 2 Diabetic Adults Insufficiently Controlled with Metformin: Study Protocol of an Open-Label, Multicenter, Non-Inferiority Parallel-Group Randomized Controlled Trial

INTRODUCTION: The prevalence of type 2 diabetes (T2D) has risen substantially in China, where its pathophysiology is primarily characterized by insulin resistance (IR). Alleviating IR may help with the management of T2D in the Chinese population. Pioglitazone and sitagliptin are two hypoglycemic medications with different pharmacological actions, both of which are optimal choices for use in combination with metformin. Previous studies have yielded mixed findings regarding the differences in hypoglycemic effects between the two agents. Though pioglitazone is associated with weight gain, both drugs have been shown to decrease visceral adipose tissue (VAT) and improve IR in individuals with T2D. There is a lack of direct comparisons between pioglitazone and sitagliptin among Chinese individuals with T2D. Therefore, this paper describes a protocol for a randomized controlled trial (RCT) that investigates the differences in hypoglycemic efficacy, IR improvement, and safety profiles between these drugs. METHODS AND ANALYSIS: This is a 24-week, open-label, multicenter, non-inferiority parallel-group RCT with a 1:1 allocation ratio. It compares pioglitazone/metformin (15 mg/500 mg) combination therapy with sitagliptin/metformin (50 mg/500 mg) combination therapy in Chinese adults with T2D insufficiently controlled with metformin. The primary outcomes are HbA1c reduction, insulin level increase, and IR index change. The secondary outcomes are body weight and abdominal VAT decreases, lipid profiles, and inflammatory indicators. Tolerability and safety data will also be collected. CONCLUSION: It is believed that the direct comparisons of the hypoglycemic effects, VAT reductions, and safety profiles between pioglitazone and sitagliptin will help to optimize treatments for Chinese adults with T2D who are primarily characterized by IR. TRIAL REGISTRATION NUMBER: Chinese Clinical Trial Registry (ChiCTR1900021861).