Hm, I've seen agave nectar touted as a great alternative to sugar, it's been served at a lot of the fertility retreats I attended while writing my fertility article for Natural Health. I know the jury's been out on it, but it IS true that I haven't been able to find any historical evidence that it's a food that ancient people used (not like the way it's been distilled into alcohol spirits), and I have seen it being possibly linked to miscarriage (because of the saponins) and so I am inclined to agree with Dr. Mercola and at the very least suggest that things are murky enough that you might want to stick with truly natural sweeteners like honey (and in moderation)!
If it's true that it causes insulin resistance, that's something that can REALLY screw up your fertility...
From Mercola.com Agave syrup has the highest fructose content of any commercial sweetener -- ranging from 70 to 97 percent, depending on the brand, which is FAR HIGHER than high fructose corn syrup (HFCS), which averages 55 percent.
This makes agave actually WORSE than HFCS.
It is important to understand that fructose does not increase insulin levels, which is not necessarily good as what it does do is radically increase insulin resistance, which is FAR more dangerous. You see, it’s okay for your insulin levels to rise, that is normal. You just don’t want these insulin levels to remain elevated, which is what insulin resistance causes.
That is why fasting insulin is such a powerful test, as it is a very powerful reflection of your insulin resistance.
In addition to insulin resistance, your risk of liver damage increases, along with triglycerides and a whole host of other health problems, as discussed in this CBC News video about the newly discovered dangers of high fructose corn syrup . The study discussed in this news report is about HFCS, however, it's well worth remembering that agave contains MORE fructose than HFCS, and in all likelihood, it's the FRUCTOSE that is causing these severe liver problems.