My husband drinks 1-2 gallons of milk everyday and often says he craves it. He has DM type 2, uncontrolled.

Gallons. 1-2 gallons of milk a day is excessive unless he drinks fat free milk. Uncontrolled DM2 is asking for trouble. He needs to see a diabetes educator!
My opinion. It's not a good idea for your husband to drink milk. Milk is a lactose sugar. Not only does it cause him to gain weight, but it also is difficult to control blood sugars.Please tell your physician what your husband is doing so he can address his problems and bring his diabetes under control. This is most important!