This scenario seemed to explain the fact that glycosuria will often vanish when mild diabetics fast or refrain from eating sugar and other high-carbohydrate foods. It also explained why some individuals could eat sugar, flour, and white rice for a lifetime and never get diabetes, but others, less able to assimilate glucose, would become diabetic when they consumed too many refined carbohydrates. Anything that slowed the digestion of these carbohydrates (like eating carbohydrates in unrefined forms) and so reduced the strain on the pancreas, the organ that secretes insulin in response to rising blood sugar, or anything that increased the assimilation of glucose without the need for insulin (excessive physical activity), might help prevent the disease itself. “If he is a poor laborer he may eat freely of starch,” Allen wrote, “and dispose safely of the glucose arising from it, because of the slower process of digestion and assimilation of starch as compared with free sugar, and because of the greater efficiency of combustion in the muscles due to exercise. If he is well-to-do, sedentary, and fond of sweet food, he may, with no greater predisposition, become openly diabetic.”

Diabetes seemed very much to be a disease of civilization, absent in isolated populations eating their traditional diets and comparatively common among the privileged classes in those nations in which the rich ate European diets: Sri Lanka (then Ceylon), Thailand, Tunisia, and the Portuguese island of Madeira, among others.*29 In China, diabetes was reportedly absent among the poor, but “the rich ones, who eat European food and drink sweet wine, suffer from it fairly often.”

To British investigators, it was the disparate rates of diabetes among the different sects, castes, and races of India that particularly implicated sugar and starches in the disease. In 1907, when the British Medical Association held a symposium on diabetes in the tropics at its annual conference, Sir Havelock Charles, surgeon general and president of the Medical Board of India, described diabetes among “the lazy and indolent rich” of India as a “scourge.” “There is not the slightest shadow of a doubt,” said Charles’s colleague Rai Koilas Chunder Bose of the University of Calcutta, “that with the progress of civilization, of high education, and increased wealth and prosperity of the people under the British rule, the number of diabetic cases has enormously increased.” The British and Indian physicians working in India agreed that the Hindus, who were vegetarians, suffered more than the Christians or the Muslims, who weren’t. And it was the Bengali, who had taken on the most trappings of the European lifestyle, and whose daily sustenance, noted Charles, was “chiefly rice, flour, pulses*30 and sugars,” who suffered the most—10 percent of “Bengali gentlemen” were reportedly diabetic. (In comparison, noted Charles, only eight cases of diabetes had been diagnosed among the seventy-six thousand British officials and soldiers working in India at the time—an incidence rate of .01 percent.)