Characteristics of subjects with type 2 diabetes enrolled in randomized controlled trials and non‐randomized controlled trials in Japan: A systematic review

AIMS/INTRODUCTION: This study aimed to understand the characteristics of type 2 diabetes subjects enrolled in randomized controlled trials (RCTs) and non‐RCTs according to therapeutic regimens through systematic literature review. MATERIALS AND METHODS: PubMed and the database of the Japanese Medical Abstract Society (ICHUSHI) were searched for studies published from 2010 to 2019 reporting the efficacy and safety of glucose‐lowering drugs in Japanese individuals with suboptimally controlled type 2 diabetes, and therapeutic regimens, demographics and clinical characteristics at the baseline were extracted. We evaluated the treatment arms, not the placebo arms. RESULTS: The literature searches identified 2,656 publications, 145 of which met all eligibility criteria and included 282 eligible arms. In the past 10 years, dipeptidyl peptidase‐4 inhibitor was the most frequently studied in both RCTs and non‐RCTs. Regarding the characteristics of enrolled subjects, sodium–glucose cotransporter 2 inhibitor and glucagon‐like peptide‐1 receptor agonist have been studied more in relatively obese subjects, and insulin has been studied in higher proportion of subjects with disease duration ≥10 years. Most of the RCTs included subjects aged 55–64 years, whereas a higher proportion of dipeptidyl peptidase‐4 inhibitor and insulin arms in the non‐RCTs included those aged ≥65 years. Dipeptidyl peptidase‐4 inhibitor and sodium–glucose cotransporter 2 inhibitor were evaluated in subjects with no abnormalities in blood pressure or lipid parameters; however, only a few reports of those parameters have been assessed with glucagon‐like peptide‐1 receptor agonist and insulin. CONCLUSIONS: As RCTs and non‐RCTs differ in the baseline characteristics of type 2 diabetes subjects, it is necessary to integrate and evaluate both to understand the actual treatment status of type 2 diabetes.