For evaluating response to antihypertensive treatment, guidelines recommend to measure the SBP after 2–4 weeks. This corresponds with improvements in mean SBP levels we observed after 10 days, indicating that a minimum period of 2 weeks could be used as Adriamycin 25316-40-9 adequate for response to antihypertensive treatment evaluation. For lipid-lowering treatment, the Dutch guideline states that an evaluation should take place after several weeks, which we defined as 3 weeks. The American guideline recommends a minimal period of 6 weeks for response to treatment evaluation. Our findings indicate that a minimum period of 3 weeks could be used to reflect adequate response to lipid-lowering treatment evaluation. Regarding evaluation of response to RAAS-i treatment in case of albuminuria, it has only been stated that repeated testing is reasonable, but guidelines recommend only annual routine testing of ACR. In our study, no firm conclusions can be drawn due to the small numbers of patients with recurrent ACR tests. The strength of our study is that it was conducted using a nonrestricted population of primary care patients with type 2 diabetes using data from medical records. It reflects quality of diabetes care in the northern part of the Netherlands which may differ from other countries. This is, for example, the case in the British Quality and Outcome Framework. The chosen definitions of adequate care are consistent with other international and national guidelines for type 2 diabetes. Although one might question whether treatment intensification is needed or wanted in all patients above the defined target values, especially given recent findings of published clinical trials, our study reflects quality of care as measured according to recommendations in prevailing diabetes guidelines at the time of our study. The quality measures we used were derived from these guideline, and as such can be considered content valid. There is, however, limited evidence for their predictive validity regarding patient outcomes. We considered changes in treatment after one elevated level as adequate, since in this type of longitudinal observational study this can already be a recurrent elevated risk factor measurement. We based our proposed time periods on a combination of guideline recommendations and feasibility in daily practice. Ultimately, definitions of the optimal time periods should be based on their impact on health outcomes. The effect of the time period definitions on quality assessment is likely to depend on reimbursement, and local or national organization and agreements for regular or standard care. In the Netherlands, as in many other countries, diabetes patients usually have a regular visit with their health care provider every three months. Our predefined time periods may be less applicable for settings where this is not the case. To assess too early response to treatment evaluation, we chose 10-day and 20-day intervals to have sufficient numbers of patients on the one hand, and clinically meaningful time intervals on the other. For albuminuria, however, this resulted in small numbers of patients per interval and unreliable outcome estimates.