We have a health improvent app which targets the 89 million estimated us with prediabetes. V1 is iPhone only, 63 million users. How do we estate the total addressable market without specifying the income demographic ? Is that possible?
This 2012 study from Deloitte may give you some insights for extrapolating an estimate: http://www.deloitte.com/assets/Dcom-UnitedStates/Local%20Assets/Documents/us_chs_2012_mhealth_HowMobileTechnologyIsTransformingHealthCare_032213.pdf
For example, 247 million people have downloaded a healthcare app. 60% were for weight loss and exercise. Of the 13, 600 downloaded for iPhone, 5.3% were for chronic conditions. "Mobile technology supports increasing consumer engagement in wellness, prevention, and treatment programs, as well as chronic disease management. Pilot studies in diabetes and hypertension management have shown improved outcomes through remote monitoring."
If you main objective is to know if there's a market for your app, then I would suggest to log on to your iphone and search for "diabetes". Then log on to appannie.com and try to see if some of these apps are successful (check their ranking, you might need to create a free account for that). You won't be able to know how many downloads they are getting... but if I see it I might give you a rough estimation. If no apps are successful, then there is no demand