[1] It is not an evidence-based cancer treatment, and the costs of IPT are not covered by health insurance.
[2] According to Quackwatch, "Insulin Potentiation Therapy (IPT) is one of several unproven, dangerous treatments that is promoted by a small group of practitioners without trustworthy evidence that it works.
Originally, Garcia targeted syphilis, and later tried the treatment for chronic degenerative diseases and some types of cancer.
[2] The other idea is that insulin might cause the cells to start dividing, which makes them more susceptible to destruction of many cytotoxic chemotherapy drugs.
[2] Patients pay the full cost out of pocket, because it is an unproven therapy that is not covered by health insurance.