A Swedish study involving almost 65,000 people suggests women with high blood sugar are more likely to develop cancer.
A team led by Dr. Par Stattin at University Hospital in Umea, Sweden, invited people who were 40, 50 or 60 years old to join the study in the mid-1980s. The study involved more than 33,000 women and 31,000 men who were followed for an average of eight years. None of the participants was diabetic, smoked or had a personal history of cancer other than the less serious forms of skin cancer.
During the study period, nearly 2,500 new cases of cancer were diagnosed. Women in the top 25 per cent range of blood sugar readings had a 26 per cent greater chance of developing cancer than those in the bottom quarter. These cancers included tumours of the breast and the lining of the uterus.
Among all the participants with high blood sugar, there were higher risks for pancreatic cancer, urinary tract cancer and malignant melanoma, the most serious form of skin cancer, but these risks were greater in women than in men.
High blood sugar could be a sign of elevated risk for diabetes, a chronic condition in which the body doesn't produce enough of the hormone insulin, or doesn't respond properly to it. But diabetes experts have raised questions about the study, saying the researchers did not gather enough information on the participants, such as diet and exercise habits, insulin levels, or family history of cancer.
Jeffery Johnson, Canada Research Chair in Diabetes Health Outcomes at the University of Alberta in Edmonton, says it makes sense that high blood sugar is related to cancer, but it may be abnormally high levels of insulin that are the culprit, rather than the sugar itself.
"Also, the authors did not report how many people went on to develop diabetes, nor did they report the type of medications that might have been used for those who did develop diabetes. Recent research, including that by our own group, would suggest that the type of treatments for diabetes may have an impact on the subsequent development of cancer."
The Swedish research was partly funded by the World Cancer Research Fund. Dr. Greg Martin, science and research manager for the fund, says it's important that women know the findings. But the good news, he adds, is that people can reduce blood sugar levels by eating a healthy balanced diet.
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