Milk will affect each of us slightly differently, as will most foods in fact. But in all of us, it will raise blood sugar since it contains a reasonable amount of lactose (5%), a disaccharide comprising one molecule of glucose and one molecule of galactose. In the digestion, these simple sugars are released and the results will show up on you glucose monitor. I once woke up with a low b.s. (40) and thought I'd take the edge off it with a large slug of milk straight from the fridge - nothing else. Next time I checked, my monitor read 137!!! I don't drink milk anymore.
There's no fructose in milk, fructose is a fruit sugar. If you reduce the proportion of fat in milk, you effectively increase the proportion of lactose in the remaing milk. In other words, the less fat in the milk, the more sugar and the greater the impact on your blood sugar. This is precisely the same principle which makes processed low-fat foods a very poor choice, not only for diabetics, but for anyone. The fat is the healthiest bit! If you use milk at all, I'd suggest whole milk as the best choice.
As for the dried, powdered varieties, I'm struggling to find a reason for using that at all. You'd need to look closely at the ingredients panel - anything in there ending in -ose and best steer clear I'd say.
All the best,