Dear Ms. Honey,
Good for you! But make sure that you don't beat yourself up! -- there's only so much you can do. Try to learn as much as you can about diabetes, but the most important thing you can do as a daughter is to just be there for your father, and encourage him to get healthier.
I was fortunate -- because of my background in biochemistry, I was able to help my father (who also has a background in biochemistry and engineering science), so my father was able to help himself overcome his near-death coma and insulin shots to beat his diabetes. As a result he started helping other diabetics by working as a diabetic support group volunteer for the American Diabetes Association. He shared with them what foods he ate (e.g. Brussel sprouts, broccoli) and what foods he avoided to get healthier (e.g. bread, pasta, cereal). To help my father spread his story, I encouraged him to set up a website (deathtodiabetes.com) and write a book (Death to Diabetes). My father didn't want to write a book, but when his mother demanded that he write a book, he had no choice.
I had to take off work for several weeks to help my father get around when he got out of the hospital. I helped him with his blood glucose testing, recorded the blood glucose data, and put the data into an Excel spreadsheet, which made it easier to analyze his blood glucose readings. My father said that the most important thing I did was to cook/prepare healthy meals for him -- my father wasn't much of a cook so I had to show him how to prepare healthy meals. His mother and one of his sisters also helped him. Because of this support, my father was able to focus on getting better and eventually (according to his primary care physician), he beat his diabetes.
When the newspaper found out about my father's miraculous recovery, they did a story about him. A copy of the story is at:
http://www.deathtodiabetes.com/uploads/file/newspaper article w DC header_v03b.pdf
I hope this is of some help to you and I wish you the best -- let me know if you want some other ideas of how I helped my father.
p.s. Currently, I am trying to help my father at various health fairs, his diabetes workshops and other events, where people ask my father questions about how he weaned off the drugs and beat his diabetes.