If there is one concept that drives much of divide in the GMO debate, it’s substantial equivalence. Having different understandings or misunderstandings of the concept leads to rancor, distrust and talking past each other.
There is strong evidence that herbicide use has indeed increased in GMO crops (corn, soybean, and cotton), much as the critics have suggested. However, the evidence also suggest that herbicide use has increased even faster in the non-GMO crops rice and wheat. This suggests that there is an overall trend for increasing herbicide use in all crops, irrespective of whether GMO varieties are available. It is even plausible, based on these data, that GMO crops have slowed the increase in herbicide use (though it is impossible to say for sure).
The balance of evidence favours the argument that adopting Bt cotton has increased yields in all cotton-growing states except Punjab, and has reduced pesticide costs so that the crop has become more profitable for farmers. So it’s reasonable to suppose that these farmers have reduced their debts and, to the extent that suicide has an economic component, are less at risk of committing suicide.