Here’s a chart showing estimates of the uninsured from two reliable sources: the CDC and the Kaiser Family Foundation.
As you can see, both ticked up slightly in 2017 by about three-tenths of a percentage point. Is this Donald Trump’s fault? It could be. He certainly tried his best. On the other hand, the CDC survey includes standard error bars, which are represented by the light blue on the chart. Any change within that light blue could be real or could just be a statistical artifact that will go away during the next few surveys.
So which is it? Well, the CDC has done two quarterly surveys so far in 2018, and the uninsured rate for January-June is down four-tenths of a point. For the time being, then, I think the best guess is that the uptick in 2017 is just a meaningless statistical artifact. Donald Trump tried his best, but in the end he accomplished nothing at all. Here’s an up-to-date chart: