Well according to some graphs I found on Google, malaria mortality rates have reduced significantly in the past few decades [1], as have AIDS death rates [2]. Diabetes rates and mortality have however been continuously increasing.

1. http://www.umich.edu/~csfound/545/1995/land05.jpg

2. http://www.drugabuse.gov/sites/default/files/images/colorbox...

So diabetes should be the easiest one to attack.

How might it be attacked, from a medicinal perspective?

We already have at least one drug that increases sensitivity to insulin. There's room for improvement, though.

Also, artificial pancreases are in the trial stage.