In the UK, a ‘carer’ is someone who, unpaid, looks after a family member, friend or partner who could not manage without them because of frailness, illness or disability. In this paper, we present research on the role of the carer, and describe why it is important to consider carers in the design of new healthcare technology to support people to self care. By self care, we mean supporting people to take more control and responsibility for their own health and well-being. Our contribution is a set of design guidelines for new home monitoring technology. Our guidelines are distilled from a survey distributed to carers in Moray, North East Scotland on sharing health information and a follow-up discussion at a carers forum. We used these guidelines to design a new home monitoring system. The main difference with current systems is that data is primarily shared between carer and cared-for, rather than health professional and patient, and carers are encouraged to use the system to monitor their own health.