Many people who lives a long life have low insulin within the normal range. And sugar spikes insulin and should be avoided. Most cenenarian do eat meat.
Robb Wolf says that …
“centenarians ALL eat red meat, typically drink a little, are go-getters in attitude.”[reference]
And in his podcast 146, he says …
“one of the things that we see as a defining element of people living longer is that
they tend to eat more protein.”
Paul Jaminet found that centenarians tend to eat two types of diets:
1) Calorie-restriction and intermittent fasting.
2) High (saturated and monounsaturated) fat low-carb diets.
Of course there are some with good genes that can eat anything and still be healthy. Look at George Burns who smokes and lives to 100.
References:
Typical Lifetime Dietary Habits of Centenarians