Indeed, for much of the last century, students in health-care professions were taught that sugar was uniquely involved in accelerating diabetes because it caused a surge in blood sugar after consumption. This surge supposedly then stressed the insulin-producing cells in the pancreas responsible for lowering blood glucose. Eventually, these cells “burnt out” from decades of overwork, so producing diabetes.
The “stress” may be real but, unfortunately, the word “sugar” has two meanings – the “sugar” you eat is different from the “sugar” measured in your blood stream. First, some basic chemistry. A molecule is a bunch of atoms joined together. The sugar in blood is a small molecule, known as “glucose”.
But the molecule in your kitchen-table sugar is a bigger molecule called sucrose, made from two small molecules stuck together, one the “glucose” found in your blood, the other called “fructose”. So yes, there is glucose in table sugar – about half. But there is glucose in the lactose molecule in milk, and in most carbohydrates such as potato and bread.
We now know all carbohydrate foods raise blood sugars, some more so than others. Surprisingly, refined sugar and sugary foods are not among the worst. In fact, potatoes and white bread are higher on the scale of blood-glucose raising capacity (glycemic index or GI) than table sugar, and there is evidence they are linked to a higher risk of diabetes.
Eating 17 slices of white bread a week had significatly higher risk than those who avoided bread.
Again surprisingly, most studies have found no links between a diet high in refined sugar and higher risk of developing diabetes. The American Diabetes Association doesn’t even mention sugars in its 2008 nutrition recommendations for preventing diabetes. Instead, it concentrates on “energy”. Excessive energy intake of any sort – whether from starch or sugar, fat or protein – will eventually produce obesity, which is the biggest risk factor for type 2 diabetes (the most common from of diabetes).
The World Health Organisation, too, says there is no need for people with or without diabetes to strictly avoid refined sugar, stating that moderate intake (about 50 grams a day) of sugars can provide for a palatable and nutritious diet. The trouble is there are good and bad starchy foods. Two large studies from the Harvard School of Public Health looked at 65,000 female nurses and 50,000 male health prefessionals. They showed that diets with a high GI factor and low dietary fibre content were associated with a doubling of the risk of type 2 diabetes in both groups. And in the nurses’ study, there was a doubling of the risk of heart attack in those consuming a high GI diet.