A high fasting serum glucose level or diabetes increases the risk for a number of cancers including those of the liver and pancreas, according to an article in the January 12th issue of the Journal of the American Medical Association.

Diabetes mellitus is a serious and costly disease that is becoming increasingly common in many countries, including Korea, the location of the current study. Recent data show that approximately 150 million people have diabetes mellitus worldwide, and this number may double by 2025, especially in developing countries, because of population growth, aging, unhealthy diets, obesity, and sedentary lifestyles.

Sun Ha Jee, PhD, MHS, and his Korean colleagues examined the relationship between fasting serum glucose and diabetes and risk of all cancers and specific cancers in men and women in Korea. The 10-year Korean Cancer Prevention Study (KCPS) included 1,298,385 adults (829,770 men and 468,615 women) aged 30 to 95 years who received health insurance from the National Health Insurance Corp. and had a biennial medical evaluation in 1992-1995.

During the 10 years of follow-up, there were 20,566 cancer deaths in men and 5,907 cancer deaths in women. The researchers found that, after adjustment for smoking and alcohol use, the group with the highest fasting serum glucose (140 mg/dL or greater [7.8 mmol/L or greater]) had a higher death rate from all cancers combined (29 percent higher for men; 23 percent higher for women) compared with the group with the lowest level (less than 90 mg/dL [less than 5.0 mmol/L]).

By cancer site, the association was strongest for pancreatic cancer, comparing the highest and lowest stratums (91 percent increased risk in men; more than twice the risk for women). Significant associations were also found for cancers of the esophagus, liver, and colon/rectum in men and of the liver and cervix in women, and there were significant trends with glucose level for cancers of the esophagus, colon/rectum, liver, pancreas, and bile duct in men and of the liver and pancreas in women.

Of the 26,473 total cancer deaths in men and women, 848 were estimated as attributable to having a fasting serum glucose level of more than 90 mg/dL. For cancer incidence, the general patterns reflected those found for mortality. For persons with a diagnosis of diabetes or a fasting serum glucose level greater than 125 mg/dL (6.9 mmol/L), risks for cancer incidence and mortality were generally elevated compared with those without diabetes.

“While the generalizability of the findings is uncertain, we have shown that fasting serum glucose level and diabetes are associated with cancer risk in a population far leaner than the Western populations in other studies. These associations do not reflect confounding by obesity, suggesting that the mechanism of increased cancer risk reflects the consequences of hyperinsulinemia. Glucose intolerance may be one pathway by which obesity increases cancer risk, and rising obesity may increase future cancer rates,” the authors wrote.

In an accompanying editorial, Kathleen A. Cooney, MD, and Stephen B. Gruber, MD, PhD, MPH, discussed the findings:

“How may these results be interpreted in the context of cancer incidence and mortality in the population? Fortunately, the relative risks are modest and, therefore, the fraction of cancers attributable to elevated fasting glucose in the Korean population is small, in part because of the relatively low prevalence of diabetes in Korea (5 percent).”

“As diabetes becomes an increasing public health concern in modern societies, the cancer risks looming on the horizon are now being recognized. Strategies to address the emerging epidemics of diabetes and obesity are likely to have a broad impact on public health. Indeed, these approaches may ultimately diminish the burden of cancer for future generations,” they concluded.