Elevated Fasting Blood Glucose is Associated with Increased Risk of Breast Cancer: Outcome of Case-control Study Conducted in Karachi, Pakistan

Background: There are several validated risk factors for breast cancer. However the legitimacy of elevated fasting blood glucose (FBG) is not well established. This study was designed to assess this parameter as a risk factor for breast cancer among pre- and post-menopausal women. Materials and Methods: This case-control study was conducted at Department of Biochemistry, University of Karachi from June 2010 to August 2014. Simple random sampling technique was used to collect data of study subjects comprising 175 diagnosed breast cancer patients with positive histopathology from Breast Clinic, surgical unit-1, Civil Hospital, Karachi and 175 healthy controls from various screening programs. Blood samples were analyzed for FBG and serum insulin. Results: FBG, HOMA-IR, systolic and diastolic blood pressure were significantly raised in breast cancer cases when compared to control subjects. Cases and controls were further categorized in to two groups using cutoff value of 110mg/dl to distinguish subjects into normal fasting glucose (<110mg/dl) and having impaired fasting glucose (${\geq}110-{\leq}125mg/dl$) or diabetes (${\geq}126mg/dl$). Odds ratios were found to be 1.57, 2.15 and 1.17 in overall, pre-menopausal and post-menopausal groups, respectively. (all p < 0.05). Conclusions: A statistically significant risk of breast cancer exists in women having elevated fasting blood glucose levels, corresponding to prediabetes and diabetes, among pre and postmenopausal ages, with comparatively greater effects in the premenopausal group.