Most people of your dad's generation ate carbs
@donnellysdogs What they did not eat was the modern Western diet comprising ready meals, take-a-ways, processed food, nasty industrialised vegetable oils, and not forgetting grazing, snacking, and huge massive portions.
My 2 grandmas lived to their mid 90's, all their many siblings did likewise, so did great grandma, my mum lived to 89, dad only managed it to 72. None had diabetes as far as they or I were aware. They ate carbs - home made pies were almost a daily occurrence. They just did not have all the rubbish that is available today, and ate 3 square meals and maybe a small light supper at bedtime. This is most likely a reason all of them lived long and healthy lives, not even a glimmer of arthritis either.