Skim milk, like regular milk, contains the natural milk sugar lactose. Plain milk (both skim and regular) does not have any sugar added. Lactose-free milk has had enzymes added which break down the lactose into more basic sugars (called galactose and glucose), however, the natural sugar content remains very similar to skim and regular milk.

Nutrition labels will show that plain milk contains an average 5g of total sugar per 100g. This is the sugar found naturally in milk (lactose). Plain milk (skim and regular) do not have any sugar added.

Lactose-free milk is an option for people who have difficulty digesting lactose. This milk has enzymes added which break down the lactose into more basic sugars (called galactose and glucose).

All types of milk are classified as Five Food Group foods in the Australian Dietary Guidelines and are considered healthy choices.

References

Australian Food Composition (Jan 2019) Database 

National Health and Medical Research Council. Australian Dietary Guidelines Canberra: Commonwealth of Australia; 2013.