A nationwide multicenter randomized controlled study （JDCS） was performed in type-2 diabetes patients. The conventional （CON） group received usual care including anti-diabetic, anti-hypertensive and anti-hyperlipidemic agents to maintain their targeted levels, and the intervention （INT） group additionally received intensive education on lifestyle modifications and adherence to treatment by telephone counselling and at each time outpatient clinic visit for 8 years. The JDCS appears to be based on an assumption that usual treatment of diabetes is appropriate for the prevention of diabetes complications, and that the lack of patients’ compliance is the major cause of unsuccessful treatments. No significant differences between the two groups were found in most of the test results （BMI, blood pressure, fasting glucose level, TC, HDL, lipoprotein-a）, use of agents, life style （energy intake, smoking and alcohol intake） at 4 years of intervention. The exercise level was higher at 5 years of intervention, and triglyceride level was lower at 8 years. The incidence of coronary heart disease, retinopathy and neuropathy did not differ significantly between the two groups, but stroke incidence was lower in the INT group. We conducted new analyses on the changes of some explanatory variables in each group. The proportion of participants with pharmacological treatment including insulin significantly increased in both groups except sulfonylureas which about 60% of the participants used at the baseline. On the other hand, those without pharmacological treatment decreased from 19% to 4% in both groups. These indicate that both groups failed in diabetes treatment together. As for the exercise and the smoking cessation, these may prevent stroke, but do not contribute to improvement of diabetes. It is not convincing enough for us to support the validity of publicizing the treatment of diabetes patients used in the JDCS study performed at 59 universities and general hospitals in Japan.
