Insulin potentiation therapy (IPT) is an alternative cancer therapy that uses insulin to potentiate the effects of chemotherapy and other medications. This therapy was developed in Mexico by Dr. Donato Perez Garcia in the 1930s and has been used together with other unconventional therapies ⁽¹⁾. Advocates of IPT believe that cancer cells consume more sugar than healthy cells and are therefore more sensitive to insulin and insulin-like growth factor (IGF) ^(2) (7). Insulin is also believed to increase the permeability of cell membranes, increasing the intracellular concentration and cytotoxic effect of anticancer drugs ⁽¹⁾. According to the theory underlying this therapy, if cancer cells can be activated by exogenous insulin, a reduced dose (up to one-tenth the normal dose) of a chemotherapy drug can provide the same cytotoxic effects with less severe adverse reactions. The pharmacokinetic profiles on concurrent use of insulin and chemotherapy drugs are lacking and it is unclear whether insulin also potentiates toxic effects of chemotherapy on healthy cells. Exploratory studies suggest some benefit with a combination of chemotherapy and IPT ^(9) (10), but well-designed clinical trials have not been conducted.

Many of the medications used in IPT, such as insulin and other chemotherapy drugs, are FDA-approved but IPT clinics administer them “off-label.” Furthermore, some clinics that administer IPT are not operated or staffed by oncologists. Side effects of IPT include hypoglycemic reaction. A systematic review of 21 studies showed a correlation between circulating levels of IGF-I, IGFBP3 (IGF-binding protein) and an increased risk of common cancers ⁽⁸⁾.