A new study published in Diabetologia shows a link between prediabetes–when blood sugar levels are higher than normal but don’t yet qualify as diabetes–and cancer.
More than one in three U.S. adults 20 years and over have prediabetes, according to a recent Centers for Disease Control report. Even more concerning, 90% of those affected don’t know they have it. And 15-30% of people with prediabetes will develop full-blown type 2 diabetes within five years, the report says.
The meta-analysis looked at 16 studies, including data from almost 900,000 people. Researchers found a 15% higher risk of cancer associated with prediabetes, especially in the liver, stomach, pancreas, breast, and endometrium. The association stuck even after controlling for body mass index (BMI), a risk factor for both diabetes and cancer.
However, prediabetes was not associated with an increased risk of cancer of the prostate, ovary, kidney, bladder, or lung.
The study authors speculate that the consequences of high blood sugar, like chronic oxidative stress and hyperglycemia, may act as carcinogens. And factors related to insulin resistance, a hallmark of diabetes and prediabetes in which the body becomes less able to use insulin to break down sugars, may cause cancer cells to proliferate.
“Although these results are unlikely to completely explain the epidemiological association between prediabetes and site-specific cancer,” they write, “they provide a new insight into a possible direct causal link.”