Weirdly, I’m halfway through reading a rather old (2006) Design Council publication which includes a short case study on helping people with diabetes make better lifestyle choices.

Page 12-13 “Seeds of a new approach”
http://www.designcouncil.org.uk/Documents/Documents/Publications/TransformationDesign_DesignCouncil.pdf

Might be interesting, if perhaps not relevant.

Or relevant but not interesting.