Functional Medicine (FM) is an integrative model being embraced and used by all types of health care practitioners (DCs, MDs, DOs, etc.). It is not only a "white-hot" health care product, but also the future of health care in this country.
FM is a clinical & integrative model that truly looks at the entire person in an attempt to understand the underlying mechanism(s) associated with a set of symptoms or disease. FM employs diagnostic testing (much of which most doctors, including many MDs, don't even know exists), looks at the optimal values (not the sick ranges that all lab gave the Medical Doctors) and leans on cutting edge research in order to understand the root causes of sickness and disease. Once a comprehensive diagnosis is reached an FM doctor will customize a care plan that deals with the root underlying mechanism.
A great example is Type II Diabetes. Many doctors, whether they are prescribing physicians or "natural" doctors, will put their focus on lowering and controlling the patient's blood sugar, finding the organ stressors and optimize the entire body. They do this with drugs and/or nutritional products and/or herbal medicine and/or diets & food combining and/or exercise & mindful movement and/or homeopathy, etc.