Virtually everyone knows that sugar has something to do with diabetes — sugar diabetes, the sugar, or a touch of the sugar are all colloquial phrases that mean diabetes in some communities. Blood sugar is a common phrase substituted for the more precise blood glucose. Sugar affects diabetes, but sugar’s role in diabetes may not match what you think of when you hear the word sugar.
To you, sugar most likely means common table sugar. To biologists and chemists, the word sugar describes a particular kind of organic molecule belonging to a category of similar molecules called carbohydrates.
Carbohydrates — the word actually means carbon with water — often follow the formula C-H2O, and the numbers of carbons and hydrogens and oxygens can go into many thousands when joined together. Sugars are the simplest carbohydrates, and in the world of food, the simplest of the simple sugar molecules are called monosaccharides. Glucose and fructose are two monosaccharides that may be familiar to you.
Disaccharides, which are two monosaccharides joined together, include sucrose, common table sugar, the milk sugar lactose, and maltose, a sugar familiar to beer drinkers. Table sugar is one molecule of glucose, and one molecule of fructose. Oligosaccharides, containing up to ten monosaccharides in a chain, are common in legumes like beans.
Carbohydrate digestion works to break chains of sugar molecules into their monosaccharide building blocks. In your diet, simple sugars and disaccharides can be absorbed rapidly, and the glucose component can have an immediate effect on blood glucose levels. When sugars are not naturally packaged in their original state like an apple or a beet — added sugars like sucrose — sole nutritional benefit is in the calories.
But, in an affluent society, added sugars usually add up to excess calories, and with diabetes in the equation the rapid rise in blood glucose levels makes control more difficult.
Even among individuals without diabetes, this spiking of blood glucose and insulin levels seems to have long term consequences. And diets high in excess, added sugar clearly contribute to obesity and increase the risk for diabetes and heart disease.
The bottom line on sugar is that it’s best eaten in its natural form, for example from fruit, instead of as a refined, added sweetener. Longer-chained saccharides, like the oligosaccharides in legumes, are another excellent dietary source of sugars.