Higher dietary glycemic index, intake of high-glycemic index foods, and insulin load are associated with the risk of breast cancer, with differences according to body mass index in women from Córdoba, Argentina.

Dietary patterns based on rich-carbohydrate foods were associated with breast cancer (BC) in Córdoba (Argentina). Nevertheless, the effect of dietary indicators of postprandial blood glucose or insulinemia on this cancer has not been studied. Thus, we hypothesize that higher dietary glycemic and insulinemic indices increase the risk of BC occurrence, with differential effects according to the presence/absence of overweight. A case-control study was conducted for BC (346/596 cases/controls) in Córdoba, Argentina, from 2008 to 2016. Multiple logistic regression models were used to assess the effect of glycemic index (GI), glycemic load, insulin index, and insulin load (IL) and the intake of high-GI foods (HGIF) on BC occurrence, adjusted by specific confounders and stratified by body mass index (BMI, <25 or ≥25 kg/m2). The odds ratio (OR) for BC occurrence comparing the highest versus the lowest tertile of dietary GI was 1.77 (95% confidence interval [CI], 1.19-2.64). Additionally, a positive association between the weekly intake of HGIF and the dietary IL was found (OR, 1.71; 95% CI, 1.14-2.55 and OR, 1.50; 95% CI, 1.03-2.19, respectively). In normal-weight women, dietary GI and IL were associated with cancer occurrence, whereas in overweight women, only weekly intake of HGIF was associated. Our findings suggest that the BC risk related to hyperglycemic and hyperinsulinemic diet changed according to BMI. Furthermore, frequent exposure to HGIF has a relevant role in BC occurrence and its promoting effect is even higher in the presence of overweight.