Hyperinsulinemia in patients with colorectal cancer

It has been reported that non-insulin dependent diabetes mellitus (NIDDM) is one of the risk factors for colorectal cancer. Usually, in the pre-NIDDM state, hyperinsulinemia is seen for 5 to 8 years. Insulin is the growth factor of epithelial and cancer cells of colon and rectum. In this study, we evaluate glucose tolerance in the patients with colorectal cancer who were never diagnosed with DM.

We studied 82 patients with colon cancer who were never diagnosed with DM. 75-g glucose tolerance test (75g GTT) was performed and we measured serum glucose (BS) and insulin (IRI) levels, and we defined them as normal glucose tolerance (NGT), impaired GT (IGT), and DM. We also defined hyperinsulinemia as highest IRI levels over 100mU/mL at 75g GTT.

Serum glucose and insulin levels were higher in the patients with colorectal cancer than in healthy controls. In 82 colorectal cancer patients, 39 were IGT and 5 were DM. All DM patients also had hyperinsulinemia. Only 14 patients (17%) had NGT and normal IRI levels.

Our findings suggest that hyperinsulinemia is occasionally seen in patients with colorectal cancer. Hyperinsulinemia may be one of the causes of colorectal cancer and we have to control hyperinsulinemia to prevent recurrence of colorectal cancer even after curative resection.