About one of every two American adults has or is at risk of having diabetes, with approximately a third of those with diabetes unaware they have it, finds a new study that offers important insights into cancer risk. People with type 2 diabetes are at increased risk for many of the most common cancers, including liver, colon and postmenopausal breast.
The study was published in The Journal of the American Medical Association.
Research links people with type 2 diabetes at approximately twice the risk of developing cancers of the liver, pancreas and endometrium. Evidence is weaker but still clear – approximately 20 to 50 percent higher – for cancers of the colon/rectum, post-menopausal breast and bladder.
Study authors used various national health survey data conducted periodically from 1988 to 2012. Participants had answered health questions and gone in for an exam, where they gave blood samples and had their weight and height measured. Anyone who reported a previous diagnosis of diabetes went into the diabetes category. Those with various measures of blood sugar levels over a set amount were categorized as having either undiagnosed or pre-diabetes.
Using one set of measures with the most current available data (2011-12), 14 percent of adults have diabetes. Yet about a third of those with signs of the disease have not been diagnosed. Another set of blood sugar measures puts the figure at 12 percent of adults having diabetes with a quarter of these people having the disease undiagnosed. And another third of adults – slightly more – have prediabetes, a condition that shares many risk factors with common cancers.
Accounting for age, diabetes increased from approximately 10 to 12 percent in the late 1980s to the mid 2000s, where it remained until 2012.
Diabetes cases increased over time in every age group, in both sexes, and in every racial and ethnic group.
The overall increase over the decades may be due to rising rates of obesity, write the authors, a key risk factor for the disease. Obesity is also a key risk factor for increased risk of many of the most common cancers. Along with excess body fat, type 2 diabetes and cancer share several other risk factors, including poor diet and inactivity. High blood sugar is one possible mechanisms linking the two diseases; others include high levels of insulin and inflammation.
Sources: Andy Menke et al. “Prevalence of and Trends in Diabetes Among Adults in the United States, 1988-2012.” JAMA. September 8, 2015, Vol 314, No. 10.
Edward Giovannucci et al. Diabetes and Cancer: A Consensus Report, published in CA: A Cancer Journal for Clinicians. Volume 60, Issue 4, pages 207–221, July/August 2010.