Dietary Glycemic Index, Glycemic Load, and Digestible Carbohydrate Intake Are Not Associated with Risk of Type 2 Diabetes in Eight European Countries

on behalf of the InterAct consortium, Ivonne Sluijs, Joline W.J. Beulens, Yvonne T. van der Schouw, Daphne L. van der A, Genevieve Buckland, Anneleen Kuijsten, Matthias B. Schulze, Pilar Amiano, Eva Ardanaz, Beverley Balkau, Heiner Boeing, Diana Gavrila, Verena A. Grote, Timothy J. Key, Kuanrong Li, Peter Nilsson, Kim Overvad, Domenico Palli, Salvatore Panico, J.R. Quirós, Olov Rolandsson, Nina Roswall, Carlotta Sacerdote, María-José Sánchez, Sabina Sieri, Nadia Slimani, Annemieke M.W. Spijkerman, Anne Tjønneland, Rosario Tumino, Stephen J. Sharp, Claudia Langenberg, Edith J.M. Feskens, Nita G. Forouhi, Elio Riboli, Nicholas J. Wareham

The association of glycemic index (GI) and glycemic load (GL) with the risk of type 2 diabetes remains unclear. We investigated associations of dietary GI, GL, and digestible carbohydrate with incident type 2 diabetes. We performed a case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition Study, including a random subcohort (n = 16,835) and incident type 2 diabetes cases (n = 12,403). The median follow-up time was 12 y. Baseline dietary intakes were assessed using country-specific dietary questionnaires. Country-specific HR were calculated and pooled using random effects meta-analysis. Dietary GI, GL, and digestible carbohydrate in the subcohort were (mean ± SD) 56 ± 4, 127 ± 23, and 226 ± 36 g/d, respectively. After adjustment for confounders, GI and GL were not associated with incident diabetes [HR highest vs. lowest quartile (HR(Q4)) for GI: 1.05 (95% CI = 0.96, 1.16); HR(Q4) for GL: 1.07 (95% CI = 0.95, 1.20)]. Digestible carbohydrate intake was not associated with incident diabetes [HR(Q4): 0.98 (95% CI = 0.86, 1.10)]. In additional analyses, we found that discrepancies in the GI value assignment to foods possibly explain differences in GI associations with diabetes within the same study population. In conclusion, an expansion of the GI tables and systematic GI value assignment to foods may be needed to improve the validity of GI values derived in such studies, after which GI associations may need reevaluation. Our study shows that digestible carbohydrate intake is not associated with diabetes risk and suggests that diabetes risk with high-GI and -GL diets may be more modest than initial studies suggested.