As far as artificial sweetners you can suggesst your father in law to take stevia I done some research on it I and learned that actually helps to reduces diabetes, rather than promoting it (like all the artificial sweetners).
I suggest you to read a book called Sindrome X, I just read it and I found in this book that high blood pressure is also related it to Sugar and insulin. This book also have a lot of sugestions on vitamins, minerals, and herbs that help to reverse diabetes.
I hope this help you