Sorry to hear of your dad's illnesses. You'll find a lot of support here. I would recommend sitting down to talk with him about how very important he is and how you will be there for him if he needs your support.
Sorry this is brief but I need to run...will touch back shortly...I'm sure some others will chime in soon.
Hi, Lucy and welcome to the forum! It certainly does sound like your dad has liver disease, most likely cirrhosis. Was he, or is he, a heavy drinker? Could he have been exposed to hepatitis? The diuretics are for the ascites.
I agree with PG that you should sit down with him and calmly let him know that you are aware he has diabetes and liver disease and want to help him. Tell him you are an adult now and can handle the truth.
Please let us know how it goes.
Lucy, he could be a functional alcoholic. Actually, with his diabetes, elevated BP and high cholesterol, he should not have been drinking at all. What the doctor said could be true--that the liver disease is a complication of the other health problems. Generally, though, it will be the kidneys that start to fail. However, cholesterol meds can harm the liver. While a patient is on them, they generally have to have liver function tests.
Good luck with your talk and let us know how it went.