| If your husband is indeed T1 then he will definitely need insulin because he will not be producing any himself. At the moment he sounds like he is in the final stages of developing T1, whereby the pancreas is still producing some insulin, but not enough. This is why the tablets are working becuase they are boosting the effectiveness of this insulin, but these tablets will be ineffective fairly soon.
I would also raise concerns about your husband's weight. If he is very thin and still eating unhealthily and not exercising, this would suggest he has been developing diabetes for some time - one of the major symtoms of diabetes is acute weight loss despite no particular reason for weight loss. When I was dxed at 14 I had dropped from 8 stone to 6 stone within 6 months, which is pretty dramatic, to say the least.
His eye problems are also a major warning sign for diabetes, though I would suggest that he does not have permenant damage (yet) and if he gets his sugar levels under control, he will find his vision will improve again.
As for his dad - I would point out that it is perfectly normal and acceptable (and indeed, even desirable in some cases) for people with diabetes to drink.  | 
