It's been a constant issue for me and my GF -- and we both have diabetes.
The diet thing is always a problem.
One source of info that I've found valuable is this book, which was written by a guy who is both an MD and type 1.
https://www.amazon.com/Diabetes-Diet-Bernsteins-Low-Carbohydrate-Solution/dp/0316737844
Yeah, there's a lot of very surprising stuff I've learned recently, mostly from this book: The Diabetes Diet. The title sounds a little phony, like any other diet book, but the information is eye opening. The author is Dr. Richard Bernstein, who also wrote The Diabetes Solution, which I have yet to read.
There's a lot of BS my former doctors have told me (I was diagnosed at age 10). For instance, I was told when diagnosed to switch to skim milk. But, apparently skim milk contains the most lactose of any milk. Whole milk, or heavy cream, is the better choice. I was told all my life just to eat normally and avoid high fat and super sweet foods. But the key is limiting carbohydrate intake. So, if I were presented with a porterhouse and a bowl of grapes, the better choice for the diabetic is the steak. Even "healthy" carbs like fruits and some vegetables and grains should be avoided. It makes sense. Not sure why it took me so long to find out.
Edit: And congrats to your friend for deciding to become an M.D. The more diabetic docs the better.
Edit2: Forgot to mention that best artificial sweetener for diabetics (instead of a natural one like stevia) is probably saccharin. You can get it in tablet form without any additives. Good stuff.
Perhaps your father would listen if it's in a book coming from a doctor with diabetes himself? My father's doctor gave him this book by Dr. Bernstein - he became a doctor because all the things his doctors were advising him to do for his diabetes were killing him. It's totally compatible with keto as he uses low-carbohydrates: https://www.amazon.com/Diabetes-Diet-Bernsteins-Low-Carbohydrate-Solution/dp/0316737844
Also, Dr Theodore Nieman in Seattle who explains how our body burns fat, protein, and sugar and how some of his patients have cured their diabetes by reducing sugar. http://www.burnfatnotsugar.com/diet-2.0-explained.html
Dr. Nieman's website has links to other doctors with similar information.
Which part of #3? You didn't specify so I'll go to google for you.
Antimicrobial effects of virgin coconut oil and its medium-chain fatty acids on Clostridium difficile. http://www.ncbi.nlm.nih.gov/pubmed/24328700'
Tip #8 is true and diabetics especially should avoid the granulated sweeteners because of this. They contain stealth sugars that will affect blood sugar levels:
carob, corn syrup, dextrin, dextrose, dulcitol, fructose, glucose, honey, lactose, levulose, malitol, maltodextrin, maltose, mannitol, mannose, molasses, saccharose, sorbitol, sorghum, treacle, turbinado, xylitol, xylose
Splenda (granulated) has dextrose and maltodextrin in it which do affect blood sugar and add carbs. The reason liquid sweetener like EZ Sweet is preferred is because it doesn't contain any stealth sugars.
This list is from the book "The Diabetes Diet" by Dr. Richard K. Bernstein and in it he advises not to use granulated sweeteners like Splenda - only liquid. It was given to me by my doctor but you can probably check it out at the library.
There are several books written on the subject of keto & the 'betes, brah. Dr. Bernstein has dropped a couple, as has Dr. Cantin.