Recent discoveries in epidemiology and molecular epidemiology suggest a link between cancer risk, cancer progression and diabetes risk factors and treatment. Obesity, physical inactivity, smoking, mal nutrition and age are common risk nominators for both diseases. Furthermore due to these risk factors, tumor patients are often comorbid with diabetes type 2. Therefore, it is an urgent need in order to meet at least one risk factor - obesity and mal nutrition - to show that - in a scientifically well-based manner - ethnopharmacology can provide views on plants with health informations. Apart from epidemiological evidence, selected botanicals have to be proven in preclinical and cellular settings, in animal studies for the proof of principle and in clinical trials for their potentials as dietary nutritional care. We have shown here for the first time according to this scientific sequencing of evaluation that a special water soluble Bitter Melon powder is a first candidate to be included into personalized diabetes type 2 and antitumor protocols as dietary supportive care to control the carbohydrate metabolism. The proof of principle to decrease blood glucose values in db/db mice by a Bitter Melon powder was demonstrated and a prospective, randomized, double-blinded and Placebo-controlled trial in diabetes type 2 patients, although continuously throughout the trial under conventional oral therapy, gave evidence for a Bitter Melon powder to be able to decrease HbA1c in a four-months intervention. This study highlights the importance of a significantly evaluated botanical as supportive diet care in tumor and diabetes type 2 patients.