Would my dad's health make the payments even higher? Also is it hard to get life insurance? Which life insurance companies have the best rates?
Yes, your father's diabetes and health issues are going to make his life insurance payments much higher.
There's no single life insurance company that has the "best" rates for a 56 year old diabetic with high blood pressure.
He'll need to shop around and compare life insurance plans for diabetics among several highly-rated insurance companies. Consider the goal of his life insurance, what he wants the life insurance to accomplish, how much coverage he needs, and for how many years.
Several factor's will impact your father's life insurance premiums, including how long he has had diabetes, the type of diabetes, how he manages his diabetes, including his medication, diet, height-to-weight ratio, etc.
Here's how you can learn about Life Insurance for Diabetes and how to compare diabetic life insurance plans.