It worries me a bit in the context of a lot of the newer people joining this forum are generally younger and less overweight. If you are in your 50's or older or have severe obesity or diabetes the risk to benefit equation is very clear, they reduce your chances of serious illness and death and any possible rare but serious side effects are easily outweighed by the benefits.
The problem is if you have a bmi of 30 and are 20 or 30 years old and go blind or get some other horrible illness as a rare and very unlikely side effect of these medications, it is a fairly tragic outcome. Younger and healthier people are less likely to have serious illness or death caused by these medications, than those who are older , sicker or diabetic, but the risk is not zero.
There is no way to measure the cost to benefit ratio medically in younger less overweight healthier people. The odds of serious illness are too low to measure accurately without vast sized studies that just are never going to happen as the costs would be impossible. Some of the serious adverse effects are going to be measurable, but are less likely to be reported to doctors honestly if the sources are not entirely legal. So there is no real trustable data on either benefits or harms.
) and not to be cause for alarm ...for at least over 50 years. 
I do need sunglasses though... 
