Is the association between dietary glycemic index and type 2 diabetes modified by waist circumference?

D ata on dietary intake characterized by high glycemic index and glycemic load and development of type 2 diabetes have been inconsistent. A total of four studies have shown positive associations (1–4). One study showed consistent associations for both glycemic index and glycemic load (1), while in the other three, only glycemic index was predictive of diabetes (2–4). In contrast, the Atherosclerosis Risk in Communities (5) and Iowa Women’s Health Study (6) showed no association between glycemic index and glycemic load with incidence of type 2 diabetes. Furthermore, studies focusing on precursors for diabetes are equally inconsistent, the majority not supporting a role of glycemic index in insulin resistance (7–9). The aim of our study was to evaluate the impact of dietary glycemic index and glycemic load on risk of type 2 diabetes in the multiethnic Insulin Resistance Atherosclerosis Study (IRAS). Given our previous findings on abdominal adiposity predicting insulin sensitivity (10), which are key risk factors for the development of diabetes (11,12), we specifically focused on the role of glycemic index and glycemic load relative to abdominal obesity and waist change.