"This is the first study to determine whether elevated glucose or insulin as measured when or shortly after a patient has had polyps removed during a baseline colonoscopy procedure increases their risk for subsequent recurrence of pre-cancerous growths in the colon," said Dr. Andrew Flood of the University of Minnesota, who is the lead author of the study published in Gastroenterology.
"The results of our study have important clinical implications with respect to maintenance of glycemic control in patients with a history of colorectal polyps," he added.
According to the researchers, study subjects with even modestly impaired fasting glucose—an early sign of insulin resistance, which itself is a precursor of diabetes—particularly had an increased risk of recurrence of the types of polyps that are most likely to progress to invasive cancer.
The study, a part of the Polyp Prevention Trial, also suggested that even a modest elevation of fasting glucose could affect a patient's risk of developing colorectal cancer. The researchers said that patients with highest levels of both insulin and glucose had an approximately 50 per cent increased risk of colorectal tumour recurrence.
They also found that among subjects with a family history of colorectal cancer, the risk of developing the disease due to elevated concentrations of insulin and glucose was even greater as compared to the overall study population.