The reason I asked about vaccinations is because sometimes they can trigger autoimmune issues. Diabetes is an autoimmune disease itself, so both your two siblings have diagnosed autoimmune issue ? I would get yourself properly checked out !!

Not sure if you read my other posts but I am having my blood tests checked at the moment and my thyroid alongside some other reading were out of range. It may be worth you having a full thyroid checked, and adrenal check (I know it can be expensive depending on where you live) I would not start making any dietary changes or doing any supplements or medications until you have hard data to base it on. Do not give up on it cilla, it's worth getting a full health check if only to rule out any issues.