Hi GLF, welcome to the forum!
There is certainly a strong link between type 1 diabetes and hypothyroidism (that is; having T1D gives you a much greater chance of developing autoimmune hypothyroidism). I'm afraid I don't know much about prolactinoma, and while I vaguely remember reading about the differences in prolactin levels between T1 and T2 diabetics I can't remember anything of use to you.
As far as getting advice and help, myown experience is that I had to research things myself. Google is your friend; for example, search on "type 1 diabetes hypothyroidism" and you'll get plenty of reading material! It takes some effort, but this is honestly the best way to learn.
It seems to me that while many autoimmune conditions are correlated, it's not necessarily true that type 1 diabetes causes other conditions. Type 1 diabetes itself is caused by something, and it could easily be that something which also causes the other problems (in much the same way that abdominal obesity doesn't cause T2D and vice versa; both are usually the effects of another problem, namely hyperinsulinemia).
All of this is a long-winded way of saying that it's very likely the best way of controlling your hypothyroidism / prolactinoma, and of avoiding further autoimmune issues, is to do the things that get your diabetes (i.e. your bloods) under good control.
How do you do this? There's a lot to learn and I'd suggest you read up as much as you can, but essentially:
- Test your blood! Seriously, you want to be testing at least 6 times per day, every day, and writing the results down. It's a pain in the a*se (or a pain in the fingertips), but the first step to controlling the condition is knowing what's going on. At first your results may be very high or very variable, and many people don't like to test when they know they'll see a high result; but you need to get over that and start testing.
- Make sure you understand how much background insulin you need, and how much fast-acting insulin for certain amounts of food.
- Eat fewer carbs. This is contrary to the typical advice you'll get from your doctor, and it's a divisive subject on this forum (and others). This is only my opinion, but the simple fact is that it's carbohydrate that causes your blood to rise sharply and require larger injections; by limiting the amount of carbohydrate you eat you have a far better chance of stabilising your bloods.
- Accept that it will take a while to get your control right, but start today. Start testing and get a picture of what your blood is doing, and try to gradually bring it down to target levels over the course of a few weeks. You'll probably feel rough while doing this, and you might find you feel hypo at times even when your blood is well above 4 as the body becomes accustomed to the lower blood levels; stick with it!
- My other advice would be to try a gluten-free diet for at least a month. There's strong evidence that gluten intolerance is linked to type 1 diabetes and other autoimmune conditions, and eliminating gluten may help your other conditions.
- Have you tried supplementing with taurine? Taurine is a protein which the body needs, but can't produce itself (so you need to eat it), and type 1 diabetics tend to be deficient. The exciting thing is that trials have shown that taurine supplementation can halt and reverse neuropathy! Seriously, there are people with neuropathy who reversed the complication and ended up pain free. The trials used 3g of taurine twice per day; it's a powder that you stir into a glass of water and drink. It's completely safe (the trials only ran for 1 year and reported safety at that timeframe, but taurine is a natural protein and 3g twice per day is nowhere near a mega-dose). I don't know what the forum rules are on posting links to online shops etc., but if a moderator indicates it's OK I'll post a link to a shop I bought mine from; it's about £20 for a kilo, which will last about 5 months, so it's not expensive! Or you can just google it; you're looking for it in powder form, not in tablets (the tablets work, but they're far more expensive).
The good news is that you can still take control of your health and improve your HbA1C. It will take a real effort but it can be done, and people on this forum will help you out where they can.
Hope that helps, please do post back with any specific questions (or even general stuff). If you can give more information on things like your current diet, insulin regime, other medication etc. it'll help us to be more precise.
Cheers,
Nick.