Context and objective: Diagnostic self-tests have become available worldwide. The most frequently performed self-tests in the Netherlands are tests to detect high cholesterol and diabetes. Since these tests can be performed without professional guidance, potential consumers need to receive independent information on the pros and cons of self-testing. The aim of this study was to develop a decision aid (DA) on cholesterol and glucose self-testing to encourage informed choice and to meet consumers' needs and expectations.Methods: A DA was developed based on previous research and medical practice guidelines. The first prototype was assessed for content by means of semi-structured interviews with experts (n=13), followed by usability tests with...