An open-label, randomized controlled trial in type 2 diabetics with hypertension, dyslipidemia, or both was reported （J-DOIT3 study）．The participants were randomly assigned to receive conventional or intensive therapy with respect to HbA1c, blood pressure and LDL-C （n=1,271 in each group），and were followed for 8.5 years at 81 clinical sites. Both the participants and doctors in charge were aware of the group assigned. The experimental design was essentially as recommended in the [Comprehensive risk management chart for the prevention of cerebro- and cardiovascular diseases 2015] from the Joint Committee consisted of 13 internal medicine-related societies in Japan, and the Japan Atherosclerotic Society Guidelines 2017. Therefore, the conclusion from the J-DOIT3 study is expected in medical field to affect the current and future medications for the prevention of atherosclerotic cerebro- and cardiovascular diseases （ASCVD）．While analyzing the results of this study，we encountered serious problems associated with the methodology, logics and its interpretations, which were summarized in this review. The follow-up study appears to be in progress as described in the Discussion, but we interpret that the intensive therapy used in the J-DOIT3 study is risky in view of currently available evidence. We propose the authors of the study to let the participants know of the results on its objective endpoint, and newly obtain Informed Consents including the potential risks of the intensive intervention based on the progress in this field after the start of this study.
