Abstract P140: Glycemic Index, Glycemic Load, and Risk of Type 2 Diabetes: Results from 3 Large US Cohorts and an Updated Meta-analysis

Epidemiologic evidence for the role of glycemic index (GI) and glycemic load (GL) in the prevention of type 2 diabetes (T2D) has been mixed. The American Diabetes Association’s nutrition recommendations for T2D prevention state that there is not sufficient, consistent evidence to conclude that low GL diets reduce T2D risk but acknowledge the role of low GI foods rich in fiber in preventing T2D. Therefore, our objectives were to 1) prospectively examine the association of dietary GI and GL with T2D in 3 US cohorts, and 2) conduct an updated meta-analysis of the previous literature including results from our 3 cohorts. We prospectively followed 74,248 women from the Nurses’ Health Study (1984-2008), 86,484 women from the Nurses’ Health Study II (1991-2009), and 40,525 men from the Health Professionals Follow-up Study (1986-2008) who were free of diabetes, cardiovascular disease, and cancer at baseline. Diet was assessed every 4 years using a validated questionnaire. During 3,738,507 person-years of follow-up, we documented 14,482 T2D cases. In pooled multivariable analyses, after adjusting for dietary and non-dietary covariates including body mass index, those in the highest quintile of energy-adjusted GI had a 34% higher risk (95% CI: 27-43%) of T2D. Participants in the highest quintile of energy-adjusted GL had a 13% higher risk (95% CI: 5-22%) for T2D. Participants in the highest tertile of GI/GL and lowest tertile of cereal fiber had about a 50% (GI, RR=1.59, 95% CI:1.47-1.73; GL, RR=1.47, 95% CI:1.32-1.63) higher risk for T2D compared to those in the lowest tertile of GI/GL and highest tertile of cereal fiber. In the updated meta-analysis (675,767 participants and 45,570 T2D cases), the summary RRs (95% CIs) comparing the highest versus lowest categories of GI and GL were 1.19 (1.15-1.24) and 1.13 (1.09-1.18), respectively (Figure 1A and 1B). Our findings provide further evidence that a high GI/GL diet is associated with a higher T2D risk. Public health recommendations for T2D prevention should incorporate GI and GL in meal planning.