I'm planning on also making this as a Christmas gift for a diabetic friend. Any recommendation as to how to make it more diabetic-friendly?

My mother has diabetes and there would be no way to make this healthy for her. People with diabetes (even if they have no weight problems) cannot process white flour and sugar. White flour is converted too quickly into glucose and can cause spikes in blood sugar. Sugar, obviously, is not healthy for diabetics at all. Some healthy diabetics choose to continue to eat sugar on special occasions, but if you are concerned for your friend's health, you should avoid giving her sugary things that she might feel obligated to eat out of politeness.
As an alternative, maybe you could make spiced nuts. For example, in this recipe the sugar is minimal: http://www.food52.com/recipes/169_salted_almonds
Or you could omit the sugar and use a substitute. Or cinnamon actually fools you into thinking that something has sugar when it does not.
This would be a nice gift if you put it in a decorative glass jar.

I posed your question to one of my colleagues--a physician who himself has Type 1 diabetes. FYI, Type 1 and Type 2 diabetes are somewhat different, but in both cases, people manage their blood sugar by limiting the number of carbohydrates they eat. A person with Type 1 diabetes will calculate how many carbs s/he is eating and adjust the insulin accordingly. My friend informed me that while he can do this, a high fat, high carb item like a danish is really hard to manage because the sugar stays in his system for a very long time. So it has to be something that he really really loves. Someone else I know who is Type 1 loves to bake, and she uses white whole wheat flour in place of white flour. Not ideal, but a girl's got to live.

People with Type 2 diabetes often also have weight issues, so they are trying to limit carbs to keep blood sugar under control, but also need to reduce calories if they are working to control the diabetes through a combination of medicine and diet. This danish is probably also not a good choice for that, but as Amanda said, you could cut out the sugar. It's a treat after all, and we all need a treat every now and then.

I would not give a gift of sweets of any kind to a diabetic. I know you are being thoughtful, but since there are just about no diabetics who are supposed to be eating sugar (and also white flour in many cases) I would be thinking non-food items or a fruit basket for that friend.

I would recommend halving the amount of sugar in the dough and skipping it in the filling. The almond paste will still be sweet, though. Hope this is helpful!