Perhaps the dietary glycemic load is not consistently related to glucose disposal and insulin metabolism due to
individual's different responses to the same glycemic load.
Glycated hemoglobin (HbA1c) is a time-integrated measurement of glucose control, and indirectly, of insulin levels.
Increased risk in colorectal cancer was seen in the EPIC-Norfolk study with increasing HbA1c; subjects with
known diabetes had a three-fold increased risk of colorectal cancer.
In a study of a cohort in Washington county, Maryland, increased risk of colorectal cancer was seen in subjects with elevated HbA1c, BMI > 30 kg/m2 , or who used medications to control diabetes.
However, glycated hemoglobin was not found to be associated with increased risk of colorectal cancer in a small nested casecontrol study within the Nurses' Health Study.
Elevated fasting glucose, fasting insulin, 2 hour levels of glucose and insulin after an oral glucose challenge, and larger waist circumference were associated with a higher risk of
colorectal cancer.
In multiple studies diabetes has been linked with increased risk of colorectal cancer, endometrial cancer, and pancreatic cancer.
It is clear that severe dysregulation of glucose metabolism is a risk factor for cancer. Foods which contribute to hyperinsulinemia, such as refined sugar, foods containing refined sugar, and refined flour products should be avoided and eliminated from a cancer protective diet.