This chapter explores DNA microarray-based biosensing as processes of biomedicalization. The practice is characterised by the leveraging and assembling of a plurality of forms, standards, knowledges, technologies and practices that support the care of data, which makes it anything than ‘direct-to-consumer’. While DNA-based biosensing, in many ways, biomedicalize, the biomedicalization thesis, however, cannot account for the intrinsic instability that pervades the practice, ranging from DNA’s sensitivity to biological processes around it to the uncertainty that pervades the practices of DIY sense-making. Making sense of their genetic data, a group of people living with a chronic illness learn how to practice prediction that best can be described as an improvised practice in which the body must be prioritised. The instabilities encountered are managed precisely because this is done with care.