The most common type of diabetes (type 2 diabetes) is the result of insulin not working properly and usually affects people over the age of 40. Overeating, being overweight and not exercising enough are important factors (what we call lifestyle factors) which can lead to this type of diabetes, especially when there is someone else in the family with diabetes.
Many people who live in societies which are undergoing rapid westernisation are developing this type of diabetes. Why ?
To find the answer we need to look back in time. Our ancestors lived and evolved in a very cold climate. Over the last 700 000 years there have been many ice ages—the last ended only 10 000 years ago. During these ice ages there was very little plant food around and people had to hunt animals for survival. This gave them a lot of protein in their diet. In other words, during the ice ages our ancestors were carnivores (meat eaters). Their bodies adapted to this way of life to help them survive on this diet—and also to help them survive times when food was scarce.
As it turned out, this protein-based diet would also have protected them from developing diabetes. This is because the main way the body copes when there is not much carbohydrate (glucose) in the diet, is to make sure that the important parts, such as the brain, get what little glucose that is available. To do this the body makes very little insulin, because the brain can use glucose without insulin. Thus the body’s demand for insulin was very small.
Since the end of the last ice age there have been many changes to the type and amount of food that we eat. First, our ancestors began to grow food crops. Agriculture changed their eating pattern from one based on animal protein to one based on carbohydrate in the form of whole cereal grains, vegetables and beans. A dietary change like this would also have changed the sugar levels in their blood. While they ate a high protein diet, the sugar levels in their blood would not have risen significantly after a meal. When they starting eating carbohydrate regularly, the blood sugar level would have increased after meals. The amount by which the sugar levels in the blood increase after a meal depends on the G.I. factor of the carbohydrate. Crops such as wheat grain, which our ancestors grew, have a low G.L factor. They would not have caused much change in blood sugar levels, so there would have been no need to use up much insulin, either.
The second major change came with industrialisation and the advent of high speed steel roller mills. Instead of eating whole grain products, the new milling procedures broke up the grain into small particles, in fact it enabled us to produce flour so fine it resembled talcum powder. The end result was highly refined carbohydrate. We now know that breaking up natural grain seeds by milling leads to an increase in the G.I. factor of a food, and transforms a low G.I. food into one with a high G.I. factor. When this highly refined food is eaten it causes a greater increase in blood sugar levels. To keep the blood sugar levels normal, the body has to make large amounts of insulin. Many of the commercially packaged foods and drinks with which we now fill our shopping trolleys, have a high G.I. factor. All this strains the body’s insulin supplies.
Thirdly, the dramatic increase over the past 50 years in the quantity of high fat takeaway and fast foods that we regularly eat has made matters even worse. So to our already high G.I. foods, we have added a lot of fat as well. Eating a lot of fat will increase body weight, which in turn makes it harder for the insulin to clear the glucose from the blood. In other words the body becomes insulin resistant—resistant to the effect of insulin. Continually eating carbohydrate foods with a high G.I. factor places even more pressure on the body’s ability to keep producing large amounts of insulin to control the blood sugar levels. Add to this insulin resistance, and you have the perfect recipe for eventually exhausting the body’s insulin supply and developing diabetes. Recent studies from Harvard University have shown that diets with a high G.I. increase the risk of developing type 2 diabetes by two to three times.
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