Another possibility, that I don't have any evidence for but just proposing for discussion...
Type 2 diabetics have difficulty dealing with carbohydrates due to insulin resistance, reduced insulin production or both.
Assuming that the total amount of carbohydrate is the same, then by consuming it in small amounts wouldn't this allow the body time to cope with it? Conversely, consuming all your carbohydrate in one meal of the day would result in a much larger glucose spike, which some consider more harmful than a generally raised level.