Two treatment protocols are proposed. Treatment A consists of self-monitoring of blood glucose and treatment B consists of usual care. Patients in the A-group are instructed to measure their blood glucose values 4 times a day (1 fasting plasma glucose concentration and 3 post-meal glucose concentrations), two times a week, on one week day, and one weekend day (no more, no less). Patients should record these glucose values in a diary. Patient will get one page with information in Dutch. No further education than for handling the device and interpreting the values is given, so that besides this intervention, there will be no differences compared with the control group like other forms of education.