Sounds like it gets used by unscrupulous people instead of PEG. From wikipedia:
Because of its adverse effects on humans, diethylene glycol is not allowed for use in food and drugs[9] (in many countries). The U.S. Code of Federal Regulations allows no more than 0.2% of diethylene glycol in polyethylene glycol when the latter is used as a food additive.[10] The Government of Australia does not allow DEG as a food additive due to its toxicity; it is only allowed at less than 0.25% w/w of DEG as an impurity of polyethylene glycol (PEG)[11] even in toothpaste.[12]