But when researchers looked at specific types of cancer, they found that both men and women with the highest blood sugar levels were more likely to have pancreatic cancer, urinary tract cancer, and malignant melanoma (the most deadly type of skin cancer) than those with the lowest blood sugar levels.
Also, the study didn't track all possible cancer influences. For instance, researchers didn't know the participants' diet, exercise habits, or family history of cancer.
Unfortunately, as the last part of this quote shows, the study doesn't actually prove anything, it just throws a bit of a question towards high blood sugar. However, while correlation doesn't prove causation, we have to consider if the link makes sense. A diet that promotes high blood sugar also promotes high insulin levels. Insulin is a very potent growth stimulator, which is why most people that have high blood sugar and high insulin also have high body fat. Insulin's purpose is to shuttle the nutrients you eat into muscle, liver, and fat storage areas. Insulin also has the ability to stimulate even more potent growth factors, known as insulin-like growth factors (IGFs). Studies have shown that individuals with higher levels of IGFs have a higher risk of developing cancer. Along with that, the preferred fuel of cancer is glucose, which the Standard American Diet supplies in abundance.
We can also consider this from the evolutionary standpoint of nutrition. High carb diets were not possible until the advent of agriculture some 10,000 years ago or so. Until that point, all humans lived as hunter-gatherers, eating animals and plant matter. Large quantities of grains were not available, so the staple carbs were roots, fruits, and vegetables. Fast forward to the 20th century when the industrial complex took over our food production and began churning out grocery stores full of cheap, high sugar products. Given that cancer is primarily a 20th century disease, along with so many others that are tied together (obesity, diabetes, etc), the logic fits.
Considering all of the other deleterious effects of a high sugar diet, it seems prudent to keep your blood sugar low by limiting yourself to a whole foods-based diet with carbs coming from fruits, vegetables, tubers, and squashes, rather than grain products like bread and pasta. Here is a short list of the effects of a high-carb diet:
- Higher Cholesterol, for those that worry about such things
- Diabetes and Double Diabetes
- An increased risk of heart attack and stroke
- Higher risk of pancreatic cancer from soft drinks, a staple of the high-carb diet.
And let's not forget that another carb-heavy staple, bread, has been linked to kidney cancer.