Sugar, Cancer and Testing

Dr. Erin Crossman, ND


Let’s briefly discuss the relationship between sugar and cancer and then touch on tests for how sugar may be impacting your body.


Most sugars consumed are converted into glucose sugar in our bodies. Glucose is a primary fuel source for most cells of the body.


Compared to a normal cell, cancer cells use glucose about four to five times faster. The transport of glucose from the blood into cells is facilitated by insulin. Cancer cells also contain more insulin and insulin receptors compared to normal cells.


Insulin resistance is a complex process where normal cells become less affected by the insulin in the blood. It becomes more difficult to get fuel such as glucose from the blood into normal cells for use. But in cancerous tissue, increases in insulin, insulin receptors, and glucose metabolism, allows insulin to act and promote growth.


Insulin resistance is shown to be associated with an increased risk of breast, colon, endometrium, esophagus, pancreas, prostate, and uterine cancers. In early stages of cancers, high insulin in the blood is seen in about 45% of cases. As cancers become more advanced, hyperinsulinism increases to around 75% of cases.


Tests for how sugar might be acting in the body include:

  • Fasting blood glucose is tested after fasting for at least 8-12 hours provides a better baseline result for comparisons. Normally your blood sugar will rise after eating. How much it rises will depend on what you ate and how well your body can digest and absorb.
  • Fasting insulin can also be tested after fasting. High fasting insulin suggests the potential for insulin resistance although the “Insulin Tolerance” test, outlined below is a better way to check for this.
  • Glucose Tolerance test is done to determine how quickly glucose is cleared from the blood. It is most commonly used to test for gestational diabetes. It does not distinguish between insulin resistance or a reduced capacity of the pancreas to produce insulin. Ablood sample is taken after at least 8-12 hours of fasting and then the patient is given a glucose drink and blood is tested again at one hour after and possibly two hours after.
  • Insulin Tolerance test is a similar procedure to the Glucose Tolerance test but with testing both blood glucose and insulin at each interval for two hours post glucose drink. This is the best way to check for insulin resistance that can be offered to patients. The gold standard for testing insulin resistance is the hyperinsulinemic-euglycemic clamp but this is only done in research studies.
  • Hemoglobin A1C glucose in the blood binds to the hemoglobin in your red blood cells. This test measures how much glucose is bound. As red blood cells have a life span of about three to four months, the test shows an average blood sugar over approximately three months. You do not need to fast in order to test this.
  • C-peptide can be used as a marker of long term pancreatic insulin secretion and a marker of insulin resistance as it has a longer half-life than insulin. The blood sample is taken after fasting.


One of the most basic yet powerful treatments to reduce cancer risk includes diet and lifestyle counselling for blood sugar control. Dietary interventions, exercise, and stress reduction are mainstays to reduce blood glucose and insulin levels as well as insulin resistance.


~ See your doctor for more information ~