Elevated blood sugar increases risk of cancer

A research article just published in PLoS (Public Library of Science) Medicine adds more evidence to the association between elevated blood sugar and cancer. The authors begin by stating:

"Prospective studies have indicated that elevated blood glucose levels may be linked with increased cancer risk...The aim of this study was to investigate the association between blood glucose and risk of incident and fatal cancer overall and at specific sites, as well as all-cause mortality, in a large study of six European cohorts including correction for random error in glucose levels.."

The Metabolic Syndrome and Cancer project (Me-Can) includes 274,126 men and 275,818 women from Norway, Austria and Sweden whose average age at the beginning of observation was 44.8 years. Over an average follow-up time of 10.4 years 18,621 men and 11,664 women were diagnosed with cancer, and 6,973 men and 3,088 women died of cancer. When the authors calculated the relative risk for glucose levels (adjusting for BMI and smoking), the data made a strong statement:

"Significant increases in risk among men were found for incident and fatal cancer of the liver, gallbladder, and respiratory tract, for incident thyroid cancer and multiple myeloma, and for fatal rectal cancer. In women, significant associations were found for incident and fatal cancer of the pancreas, for incident urinary bladder cancer, and for fatal cancer of the uterine corpus, cervix uteri, and stomach."

The authors discuss the possible mechanisms:

"Insulin and bioavailable insulin-like growth factor-I (IGF-I) are possible links between glucose and cancer; hyperglycaemia induces elevation of these hormones that stimulate tumour growth. Glucose may also have a direct tumour-promoting effect as glucose is used as an energy substrate in tumour cells, particularly in fast-growing, highly proliferative tumour cells."

They boil down their findings in this closing summary:

"In conclusion, abnormal glucose metabolism, independent of BMI, is associated with increases in risk of cancer and cancer death overall and at many specific sites. Furthermore, our data showed a linear and somewhat stronger association among women than among men, and the association was stronger for fatal compared to incident cancer."