Elevated Insulin, Glucose Raise Risk of Polyp Recurrence


By Megan Rauscher
NEW YORK (Reuters Health) Dec 10 - Data from the Polyp Prevention Trial indicate that patients with elevated insulin or glucose at the time of adenoma removal are at increased risk for recurrent adenoma. Elevated glucose is associated with a particularly high risk of developing a recurrent advanced polyp, the type with a high likelihood of progressing to invasive cancer.
"Levels of glucose that produced the increased risk in this study were actually not very high, 99 mg/dL, which is right at the border of what we would describe as impaired fasting glucose," Dr. Andrew Flood, of University of Minnesota, Minneapolis, noted in comments to Reuters Health.
"For this reason, clinicians may want to consider more aggressive management of glucose than they might otherwise among subjects who have already had one or more adenomas," he said.
Dr. Flood and colleagues analyzed fasting serum samples from 375 subjects with and 375 without a recurrent adenoma following removal of one or more adenoma identified at a prior colonoscopy. They determined baseline insulin and glucose levels as well as changes in these levels over 4 years of follow-up in the Polyp Prevention Trial.
The investigators report, in the November issue of Gastroenterology, that the odds ratio for adenoma recurrence was 1.56 for subjects in the high quartile of insulin (> 9.45 IU/mL) compared with those in the low quartile (<> 99 mg/dL) versus those in the low quartile (< 83 mg/dL).
"Even more importantly," Dr. Flood noted, the odds ratio for a recurrent polyp with advanced histology or large size was 2.43 at a fasting glucose level above 99 mg/dL. This pattern was not seen for elevated insulin.
"Thus," he emphasized, "even a modest elevation of fasting glucose into the range that represents an early stage in the progression from normal glycemic control to insulin resistance and then to diabetes resulted in a large increase in risk of recurrence for adenomas of the type that are most likely to progress to invasive cancer."
These results "fit with the theory that insulin resistance, hyperinsulinemia, and hyperglycemia promote the development of colorectal neoplasia," the researchers note in their paper.
Dr. Flood advised that "clinicians who identify subjects with adenomas and elevated glucose should be aware of the increased risk of recurrence that these patients face. And in turn, they should consider clinical approaches to help these patients achieve better management of their blood glucose."
Gastroenterol 2007;133:1423-1429.