Janus Face of Glucose and Glucose-Regulating Hormones

Background
An average person on a normal western diet consumes
0.5 kg of sugar-related carbohydrates each week, consisting of highly refined sugars in the forms of sucrose
(table sugar), dextrose (corn sugar), and high-fructose corn syrup, which comes from
many processed foods such as bread, breakfast cereals, pastries, candies, ketchup, and a plethora of soft drinks.

Since the 1850s, sugar consumption in Germany has risen 10-fold to 34 kg per person
per year. Even more dramatic findings can be made in the USA, with an explosion
in the average consumption of pure sugar from 5 lb per person per year
(1887–1890) to 135 lb of sugar per person per year in the late 1990s! This goes hand
in hand with the consequence that cardiovascular diseases and cancer was virtually
unknown in the early 1900s, but today are leading causes of death and the main reason
for an increasing mortality in the industrialized world. Therefore, it is necessary
to provide a deeper insight into the role of glucose and possible changes in the glucose metabolism in oncogenesis, especially with respect to proliferation, cell signaling and cell survival.

Metabolic Syndrome The latest statistical studies have revealed that patients with type 2 diabetes bear a higher risk for various kinds of cancer (e.g. breast, colon, kidney, liver, and pancreas) [1–3]. Type 2 diabetes can be seen as an extreme state of glucose intolerance, and is associated with elevated plasma levels of glucose as well as insulin, but also other glucose- regulating hormones are influenced by this disease. More important, this misbalanced glucose metabolism appears both a long time before and after its diagnosis, and is associated with multiple risk factors, such as increased triglyceride levels and reduced HDL cholesterol. Since most of the patients are obese, the complications mentioned are not solely specific for type 2 diabetes, but also indicators for hypertension and other cardiac diseases. All these metabolic disorders can be summarized and are best described as metabolic syndrome [4, 5].

The causes of the metabolic syndrome are still not completely understood, and up
to now there is no conclusive definition (no ICD-10 code). The actual definition for
Germany is adapted from the International Diabetes Foundation IDF [http://www.
ipm-praevention.de/docs/Metabolisches_Syndrom_2005.pdf]. A common premise
is adiposity or generally a visceral obesity. Therefore, the diagnosis of the metabolic syndrome is existent when a visceral obesity is associated with at least two additional risk factors, such as increased triglyceride levels, diabetes, and reduced HDL cholesterol (or increased LDL and cholesterol).

Excess body weight is the sixth most important risk factor contributing to the
overall burden of disease worldwide. In the UK, 12 million adults and 10% of children
are now classified as overweight or obese. Average life expectancy is already diminishing;the main adverse consequences are cardiovascular disease, type 2 diabetes andseveral cancers. Obesity with its array of comorbidities requires careful clinicalassessment to identify underlying factors and to allow coherent management. The epidemic reflects progressive secular and age-related decreases in physical activity,along with substantial dietary changes combined with passive overconsumption of energy, despite the neurobiological processes controlling food intake. Effective long-term