Unfortunatley that's not true-since the introduction of carbohydrates and alcohol on a large scale- say the last 40 years- the rates of heart disease and diabetes is going through the roof- you're right in that sticking with a traditional subsistence diet, the rates are much lower. The trick is to convince them that is what is healthiest for them. I work with Eskimos in Western Alaska- I know.
60 - re 40 - As a long time diabetic, i have studied diabetes for many years, and also lived worked and traveled among many peoples.
I have come to the concoclusion that people who survived in starvation/low carbohydrate situations (all far northern peoples - from scandanavians and russians and germans and laplanders and eskimos), and people of the deserts of the mid-east - have bodies designed by nature to survive on high protein, high fat, and low carbohydrate diets. When exposed to diets high in carbs they get sick and die, particularly from diabetes.
So, this explains, how our plains indians, who survived on the buffalo herds, have such high rates of diabetes too. Arabs and Egyptians (desert dwellers - with few carbs) also have high rates of diabetes.
Those recommending high carb diets for diabetics are actually killing them.
While Italians and south east asians eat major amounts of carbs (wheat and rice) and have low rates of diabetes.
So, look to the ancestors of your bodies to find your best diet, as one recommended diet may kill you if your body is from another area.