Does environment link cancer & diabetes?

Last week, innovative health care researchers reported their use of digital photography to hopefully increase screening for vision loss among diabetics. This week we learn some more interesting findings about diabetes, including the largest ever study of how it increases cancer risk.

Researchers in Sweden reviewed the records of over 125,000 (type 2) diabetics, comparing their cancer risks with those of the average Swede. They found diabetics at increased risks of developing 24 cancers, especially several rare types. Cancers of the liver and pancreas were 4 and 6 times more common in diabetics, and those of the kidneys, thyroid, esophagus, small intestine and nervous system were twice as likely. One surprise: Having diabetes seems to have a protective effect against prostate cancer, perhaps because diabetic men have lower levels of potentially tumor fueling sex hormones.

While its still not clear why diabetics would have an increased risk of cancer, a new study from Stanford may provide some insights. Researchers there looked at 266 different environmental variables to see how they were related to diabetes risks. They looked at the amounts of various substances measured in patients' blood and urine, and compared them to fasting glucose levels (a higher than normal level is one indicator of diabetes risk.) What they found is interesting not only for diabetics, but could, perhaps, provide at least a theory for why diabetics have higher cancer risks. Higher levels of the chemical heptachlor epoxide, PCBs, and the vitamin E in the gamma-tocopherol form were all related to higher fasting glucose levels. Beta-carotene, on the other hand, appeared to be protective. Heptachlor epoxide was a pesticide that's no longer used, but remains ubiquitous in soils, water, and food supply.

While its probably not likely that those three substances play a large role in causing diabetes or cancers, they do point to the possibility that environmental effects may link such diseases. Some health care research is also leaning towards the idea that environmental variables may interact with genetic susceptibilities, in effect flicking the genetic switch in certain individuals. Research continues to find interesting links between conditions and risk factors, for example the possibility that high fat diet may contribute directly to asthma as well as obesity.

A final diabetes study, funded by the Weight Watchers program, found that over 6-months, people who attended at least 24 support meetings while sticking to the program's diet and exercise regimen not only lost an average of 14 pounds, but also lowered their glucose and insulin levels. If sustainable over the long term, that type of progress could beat back diabetes with one-two punches against two disease risk factors: Overweight and high blood sugar.

Photo credit: The author