I wholeheartedly agree with Ipswichwitch
I had not read your DH was an insulin dependent diabetic, and a smoker. That really ramps up the risk- he is putting himself at serious risk of long-term problems- circulatory (so think neuropathies, diabetic foot ulcers, increased risk of necrosis and amputation); he is also increasing his chances of liver, kidney and heart disease and of stroke.
I will never forget the patients I treated as a junior doctor working on the GI ward. Of those who were suffering from alcohol related problems, some of these patients had been drinking the same or less than your DH. Some for many years, some for only a few. Alcohol related liver disease is no walk in the park- I wouldn't wish it on my worst enemy.
I'll also never forget one patient (call him Mr A), a man in his 60's who was admitted with "acute confusion" and some odd neurological symptoms. It turned out he was a "bit of a drinker" who drank anywhere between 50-80 units when he was off-shore (but none for weeks at a time when at work). He had developed Wernicke's encephalopathy which, despite treatment, developed into Korsakoff's dementia. This was solely due to excessive drinking over a long time. He had profound, irreversible, cognitive deficit and was totally disorientated in time and place (e.g. thought he was a PoW or an assassin at times). He ended up in a locked ward, as he was a danger to himself and potentially others (other psychiatric disorders were ruled out). Physically, his drinking left few scars though. My point is, it's not always the liver that is the worst affected organ, or the one affected first.
Of course, he (and you, I suppose, OP) could gamble that he'll be one of the lucky ones who aren't seriously affected, or who will take years of excess alcohol consumption to be seriously affected. It's up to him what he does, it's up to you whether you seek to alter his behaviour.