Updated February 2018
Linking Diabetes to Cancer: Changes for Prevention
Diabetes affects one of every ten American adults. A strong body of evidence now suggests that people with type 2 diabetes are at increased risk of developing several cancers. Yesterday, AICR Nutrition Advisor Karen Collins, MS, RD, CDN, co-presented a webinar on the connection between diabetes and cancer. Here, we asked Karen about what lifestyle steps people with type 2 diabetes, prediabetes, or anyone trying to prevent both diseases can do.
Q: What are the cancers people with type 2 diabetes are at increased risk for?
A: Research shows that the greatest increase in risk are cancers of the liver, endometrium, pancreas and bladder. Risk for Liver cancer is over two times, pancreatic is nearly two, and endometrial is two fold higher. There's a smaller increase in risk for colon and breast cancers. But because those are the leading cancers in the United States, the fact that risk increases somewhat substantially for them means a lot more cancers.
Q: As more studies have come out on the diabetes-cancer link, what's new?
A: We're seeing more and more that the link makes sense and it's not just coincidental. As we're learning about how cancer development is linked to elevated levels of insulin and inflammation, it's becoming more apparent that the metabolic abnormalities in diabetes and prediabetes – before diabetes occurs – are the perfect conditions in the body for cancer to develop.
Q: About one-third of adults have prediabetes. How does this affect their cancer risk?
A: That's the scary part: the pre-diabetes that's happening with the increase in obesity and the sedentary quality of our lives. All the conditions common between type 2 diabetes and cancer don't just appear with a diabetes diagnosis.
Most people think the damage starts at diabetes. People are not thinking about cancer, they're worried about the damage that occurs from running high blood sugars, like going blind and kidney failure. But all those things happen way down the line with diabetes. The situation today matters.
Q: What are some first steps that people at risk or with diabetes can do to reduce their risk?
A: One of the top things is weight. For people who have overweight or obesity then it's time to take action. If you have elevated triglycerides or your blood pressure is creeping up, these are signs that metabolically things are not right in your body.
You don't need a massive amount of weight loss. Research shows that for people who have pre-diabetes, even a 5 to 7 percent weight loss is enough to dramatically reduce their risk of developing diabetes.
"You're not going to lose weight in one day but it's a very positive thing to know that in one day's walk you are making a change in insulin resistance and other metabolic conditions that can make a big difference. "
Q: How does physical activity fit into the recommendations?
A: What's really exciting about the research in both diabetes and cancer is that exercising – like a 30 minute walk a day, all at once or in two to three blocks – will reduce inflammation and bring down insulin levels, which can have a dramatic effect. You will also probably feel so much better. You're not going to lose weight in one day but it's a very positive thing to know that in one day's walk you are making a change in insulin resistance and other metabolic conditions that can make a big difference.
Q: For people managing diabetes, how does counting carbs and the glycemic index relate to the diet for cancer prevention?
A: Counting carbs, with or without conscious attention to the glycemic index, can be essential for many people. But just because two foods are similar in glycemic index does not mean their total impact on health is the same. Often, if you focus on a high-fiber diet that includes plenty of vegetables, fruits, whole grains, and beans, you'll get all kinds of benefits for diabetes and cancer prevention.
This is all about looking beyond blood sugar. It's recognizing insulin resistance and inflammation and all these other things are important and seeing how foods can promote health and reduce your risk of cancer.
Q: Should a person with diabetes be doing something different if he knows he's at higher risk for cancer?
A: These people, of all people, should not be falling behind on their cancer screenings. The consensus report looked at whether medical treatment would change: the answer was no. In fact, one of the most common first-line treatments for type 2 diabetes is metformin, and it may actually help to reduce cancer risk.
Q: And for diet and exercise?
A: Having diabetes really reinforces, 'don't delay, get on this' – you can sometimes be so overwhelmed with a diagnosis of diabetes that people take their time. You can get blood sugar controlled by more medication but that's not as good in terms of overall long-term health as combining medical treatment and healthy weight and lifestyle choices. It's better to say, I'm not going to lose 50 pounds but lets get on the stick and lose 10. I'm going to start toward a 30-minute walk now.
Q: How does heart disease fit into all this?
A: That's the interesting parallel. It's been known for a while that people with type 2 diabetes are at dramatically increased risk for heart disease. Now that we know they are at increased risk for some types of cancer, with a few tweaks you can have a unified pattern of eating to reduce risk for all three.
AICR recommendations line up well with those of AHA (American Heart Association) and ADA (American Diabetes Association). There are things like red meat. In diabetes control they don't differentiate between red meat and other choices, like chicken or fish. We would recommend less than 18 ounces of red meat, even if lean, to prevent colorectal cancer. It's a pretty positive thing to know that small changes can have the triple-effect – reduce the risk of type 2 diabetes, heart disease and cancer.
Follow Karen on her blog.