By David Liu, PHD

Monday Oct 29, 2012 (foodconsumer.org) --Type 2 diabetes mellitus and insulin treatments may increase risk of lung cancer in diabetics, according to some studies.

One study led by J. Luo of Mary Babb Randolph Cancer Center, West Virginia University in Morgantown, WV showed women with self-reported treated diabetes mellitu stype 2 were 27 percent more likely to be diagnosed with lung cancer, compared with those who did not have the disease.

The study published in Diabetes Care followed 145,765 postmenopausal women aged 50 to 79 years who participated in the Women's Health Initiative study.  Of participants, 8,154 women had diagnosed diabetes at baseline and during a mean-11-year follow-up, 2,257 cases of lung cancer were diagnosed.   Information on diabetes therapy was self-reported or obtained through a face-to-face review of the medication containers participants brought to researchers at baseline. 

Women who self-reported having diabetes treated were at 27 percent higher risk of being diagnosed with lung cancer.  And those whose diabetes required insulin treatment faced 71 percent increased risk for lung cancer, compared to those without diabetes.

Lung cancer risk was not significantly associated with untreated diabetes or with the duration of diabetes.

The researchers concluded "Postmenopausal women with treated diabetes, especially those using insulin, have a significantly higher risk of lung cancer. The influence of diabetes severity and specific classes of therapy for diabetes on lung cancer risk require future study."

This is not the first study that suggests that having diabetes, in most cases, referring to type 2 diabetes mellitus, and its insulin treatment may increase risk of lung cancer. Actually,diabetes and its treatment have been associated with many other malignancies as well.

Another study published in 2012 in Diabetologia examined how the duration of diabetes and insulin therapy would affect the risk of cancer.

B. Carstensen B at Steno Diabetes Center in Gentofte, Denmark and colleagues, authors of the study, analysed data from the Danish National diabetes Register and Cancer Registry to compare cancer incidence rates in diabetic patients with the healthy population during the period from 1995 through 2008.

The researchers found diabetes patients who did not use insulin, compared to the non-diabetic population, had 100 percent and 15 percent increased risk of cancer at diagnosis and after 2 years of diabetes duration, respectively.

They also found insulin users had 400 percent and 30 percent increased risk of cancer at the beginning of diabetes treatment and after five years of insulin therapy, respectively.

These associations suggest that insulin use was associated with higher risk of lung cancer.   But the associations did not imply that the increase in risk of cancer was definitely due to insulin use.  It is possible that insulin use, diabetes per se or both contribute to the increase in cancer risk.

Risks o f stomach cancer, liver cancer, lung cancer, pancreatic cancer, and kidney cancer were increased in both non-insulin users and insulin users.  Non-insulin users also faced  an increased risk for colorectal cancer, cancer of corpus uteri, brain cancer and lymphomas.

Diabetes and insulin use did not affect incidence of breast cancer whereas among insulin users, prostate cancer risk was apparently decreased.

This study suggests that being a diabetic and insulin use may play a role in the development of lung cancer and other malignancies.

Still another study published in 2012 in Journal of Clinical Endocrinology and Metabolism suggests that treatments for diabetes mellitus type 2 may increase risk of cancers including lung cancer.

C. H. Chang at Institute of Preventive Medicine, College of Public Health, National Taiwan University in Taiwan and colleagues conducted the study and found diabetes patients who used insulin, glinides were associated with 97 percent and 16 percent increased risk of overall cancer, respectively.  The first and second generation sulfonylureas were associated with a 8 percent increased risk of cancer while the third generation did not increase the risk.

Specifically, the researchers found use of insulin and glinides was correlated with higher risks for liver cancer, colorectal cancer, lung cancer, stomach cancer, and pancreas cancer, whereas sulfonylurea was associated primarily with an elevated risk of liver cancer.

An estimated 26 million Americans suffer diabetes mellitus type 2 and an equal number of Americans live with prediabetes.   The disease is chronic and in most cases can be prevented by following a modified lifestyle including a healthy diet.

A few highly effective preventatives have been studied by researchers from India and other countries.   Curcumin, cinnamon and bitter melon are among those preventatives that prediabetes or healthy people may use to prevent diabetes mellitus type 2, for which doctors can't provide a cure although the disease is manageable with prescription drugs.