Association of glycemic index and glycemic load with multiple myeloma: a case–control study

Dietary factors, particularly those affecting insulin resistance and inflammation, may influence multiple myeloma (MM) risk. Evidence regarding the relationship between glycemic index (GI) and glycemic load (GL) and MM is still inconclusive and shows mixed results. We investigated this relationship in an Iranian population. This case–control study included 141 newly diagnosed MM patients and 348 healthy controls (ages 20 to 75 years). Dietary intake was evaluated through a validated 154-item semi-quantitative food frequency questionnaire (FFQ). Dietary GI and GL were calculated based on participants' food intake. Binary logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) across quartiles of GI and GL. Models were adjusted for potential confounders, including age, sex, total energy consumption, and other lifestyle factors. Participants in the highest quartile of dietary GI had significantly higher odds of MM compared with those in the lowest quartile (OR 3.92, 95% CI 1.84–8.34; P-trend < 0.001) after fully adjusting for potential confounders. In contrast, dietary GL was inversely related to MM only in the crude analysis, and this association disappeared after adjustment for energy intake; GL was not associated with MM in the fully adjusted model (OR 1.37, 95% CI 0.51–3.63; P-trend = 0.45). Higher dietary GI was independently associated with increased odds of MM, whereas dietary GL was not associated with MM after adjustment for energy intake and other confounders. Further large-scale prospective studies are warranted to elucidate the role of dietary carbohydrate quality in MM development.