Virtually identical results were found by the same team in a parallel study of more than 40,000 men (Diabetes Care, 1997; 20: 545-50).

These findings are the first conclusive evidence that the major cause of adult-onset diabetes is a Western diet. Thanks to Montignac, we also now have a cogent theory to explain why it happens. It is now clear that people develop diabetes in middle-age not because of obesity, a sedentary lifestyle or stress (the conventional explanations); they become diabetic because of half a lifetime’s assault on the pancreas by a diet of refined carbohydrates and processed foods.

A dietary time bomb But that’s not the end of the story. Adding a further twist of the knife, the Harvard nutritionists recently found even more evidence to condemn the modern diet. Analysing their data on the 65,000 women, they discovered another dietary risk factor - trans fatty acids. Also called hydrogenated fats, these are liberally added to processed foods to 'improve texture'. Such fats appear to increase the risk of type 2 diabetes 'substantially' (Am J Clin Nutr, 2001; 73: 1019-26).

As yet, there is no explanation for why hydrogenated fats cause diabetes. But this latest evidence, taken with the earlier findings for refined carbohydrates, is a damning explanation for the huge rise in diabetes in the young. It is yet another health time bomb lobbed at us by the food industry, as if cancer and heart disease are not already enough.

Another risk factor for the disease may be milk. Ten years ago, evidence was already accumulating that babies fed on cow’s milk formulas are more likely to develop type 1 diabetes (Diabetes Care, 1994; 17: 13-9). Although the increased risk seems relatively small, it is magnified among children with diabetic siblings.

A Finnish study has shown that feeding such infants cow’s milk formula during early infancy results in a fivefold increase in the risk of diabetes (Diabetes, 2000; 49: 912-7).

Why this should happen is not completely understood, but the culprit is believed to be the insulin content of cow’s milk, which makes the infant create human antibodies to the bovine insulin. The theory is that the baby’s insulin antibodies then react against the insulin-producing cells in the pancreas, thus damaging the cells and triggering type 1 diabetes (Diabetes, 2000; 49: 1657-65).

Factors in cow’s milk have also been suggested as the reason why type 1 diabetes is more prevalent in the northern Europe. In such countries, Friesian cows predominate as they are more suited to colder, wetter climates. It is believed that the milk of Friesian cows may contain a diabetes-precipitating protein that other cow species do not produce.

Nevertheless, that is only one of many theories regarding the environmental causes of type 1 diabetes, which still remain obscure.

However, type 2 diabetes is now much less mysterious - thanks largely to the pioneering work of Dr Michel Montignac and the remarkable way he has stood conventional thinking about the disease on its head. Tony Edwards