I really hate misinformed articles like this one, as well as the misinformed comments at the bottom. I posted a few comments to this article, and hopefully clarified a few points.
This is actually true, from what I remember(about DEG being found in e-liquid, but it's certainly not a 'key ingredient'). A certain liquid from one manufacturer was indeed found to have less than 1% diethylene glycol in their ingredients. However, this was an older study by a less-reputable liquid maker, and I'm sure it has been fixed. Unfortunately, the FDA used this report to mislead the public about e-cigarettes:
How and Why The FDA Misled The Public | Electronic Cigarettes by Instead E-Cigarette