Hi MSUSpartan,
it is really interesting to see how various this is handled in different countries. In Germany it seem to be very different compared to the US. Medical aids (like wheelchairs orthopaedic braces and also diapers) are (at last partly) covered by the national health insurance system. If it comes to diapers this is again somehow "special" because the way how this is handled depends hardly on the insurance company itself. There is a law, that bound the companies to a supply mandate for medical aids but it's up to the insurance company how they handle this in detail.
Just to make things even more complicated it's not always easily to change a insurance company. If you are lucky and the company you are working for have it's own insurance your are normaly fine because these normally make less problems compared to the public or privat companies. You can chose also the insurance company if you are over a dedicated income threshold. Otherwise you have to live with the national health insurance.
The way the insurance often deal with incontinence supplys is, thats they shift there responsibility to subcontractor (if you are not in institutional care). The subcontractor do it's business model on a mixed calculation with the assumption that the most common absorbing products are pads. Diaper are expensive and a "exception". More over he do a very simple calculation of your needs: He take mean value of your leakage over 4 hours and chose a product that is capable to take that. With this calculation normally a simple pad will do the job. If you are not happy with this it's up to you to negotiate with the subcontractor and prove him wrong.
If you simply ask for diapers, the contractor will try offers your pads or a cheap solutions in any case and try to explain you should simply change more often or that the products your asking for are oversized for your grade of incontinence. This is indeed cheaper for him because of the mentioned business model. Despite of the fact that this may sometimes also a better solution at last I can say that I prefer a individual supply that fits to my own needs. But to get this, you normally end up that you have to prove the supplier wrong and it's up to you to show that the products they are offering do not live up with your demands and the law.
On good base for this argumentation is a database from the umbrella association of the health insurances in Germany where all medical aids that can be prescribed are listed with there technical parameters (if you can read a bit German you my try this link:
https://hilfsmittel.gkv-spitzenverband.de/produktlisteZurArt_input.action?paramArtId=4514. The good thing is, that the technical parameters that have to be listed are given by law. The way the argumentation had worked for me was to take this database and check for products with the appropriate parameters. This was in my case the ABL value and the absorption speed. With this knowledge I went to my urologist and ask him to put the parameters on the prescription.
The supplier have the right to offer medical aids of his choice after a thorough consultation. How ever - he have not right to ignore the prescription from the treading doctor. So if the prescription say something like "absorbing aids for incontinence" the supplier can deliver nearly every think he want - but the more the doc specify the prescription the less freedom of choice have the supplier.
Unfortunately this is often ignored by the supplier in a first step, and this is the point were you have to start writing endlessly letters, and maybe have to involve also lawyer. I may case I had at last a little bit luck because one of the subcontractors of my insurance company was also a manufacturer - in my case Attends. It still need over 6 month before we find an gentle agreement that fits more or less for me. In the end I had to pay 15€ extra per month for the supply of 28 Attends Slip Regular 10 + 21 Attends Adjustable 10 + 56 Attends Air Comfort 7 pads per month.