Study was conducted in exemplary fashion

EDITOR>—The United Kingdom Prospective Diabetes Study has shown over 10 years of follow up that people with newly diagnosed type 2 diabetes can maintain excellent glycaemic control (concentrations of haemoglobin A_1c of 7%) and that this can significantly reduce microvascular complications.1 It has also shown that strict blood pressure control can significantly reduce mortality as well as microvascular and macrovascular complications among these people.2 The study group thus answered its primary research questions. The design of the study meant that several secondary questions could not be answered convincingly.3 Several lessons in ethics and public health can, however, be learnt.

The fact that the comparison group maintained a comparatively low concentration of haemoglobin A_1c (7.9%) over 10 years of follow up means that the researchers were ethical to the point of risking a null finding. In contrast, in their enthusiasm to establish the efficacy of specific treatment(s) some investigators replace standard drug treatment with an inactive placebo.4 The researchers continuously adapted the intervention to changes in scientific knowledge and clinical practice, which is reasonable and justifiable in a 20 year trial that chooses to adhere to sound ethical principles.

The study was conducted in primary healthcare settings rather than specialist centres or university hospitals, and the results are therefore likely to be closer to clinical practice …