Yes, Medicare and tricker (military) insurance covers diapers for any child over 3 that is not potty trained. You do not have to have a diagnosis just a doctors prescription. I doubt private insurances pay, but then again you never know. Most doctors and no state worker will tell you this unless, you have a dd case manager, and then I would tell every client. You can not pick the brand, it is all from a home health store, like the ones who sell w/c and canes, or assistive toilet seats and such. But the diapers are pretty good, especially the pull ups.
No to the formula, there is no insurance that covers that. Some state agencies may help, our health department will help, wic will help for children under 5, and our agency DDD will help most up to $1500 a year, which I know is not much but at least it is something. E work very hard with doctors who put kids, adult on these very expensive formulas, sometimes they are just getting kick backs promoting them, other times they have tried 15 others and this is all that works. We as case managers, are sometimes successful at getting companies to supply some of the formula to the family at no cost, we have been able to work with the hard ship departments of several companies, ask your social worker at the hospital or your case manager for help in getting a hardship, to help supply the formula.