From what I have seen diabectic meals are mostly likely to be low fat and contain complex carbs but will not tell you how many carbs are contained in the meal. So it all depends want you want from the meal.

As for a Kosher meal pretty sure this isn't low fat.

What are you looking for from the meal as I sense a diabetic meal compared to a kosher meal are two complete different types of meals.

Personally diabectic meals aren't for me - yes I am a Type 1 but would never order as standard meal suits what I need from a meal on a plane. But as a good diabetic always have food in my bag if nothing suits.