High glycemic index and glycemic load diets increase the risk of Type 2 Diabetes

Results from 3 large cohort studies and a recently updated meta-analysis provide additional evidence that higher dietary glycemic index and glycemic load diets are associated with an elevated risk of Type 2 Diabetes.

Type 2 diabetes (T2D) has been a worldwide public health concern for several decades. It is projected to be the seventh leading cause of death by 2030. Many good studies have shown that a healthy diet and lifestyle can be even more effective at preventing T2D than medical or pharmaceutical interventions.

In a recent study published online in the American Journal of Clinical Nutrition, researchers examined the association of dietary carbohydrate quality, using glycemic index (GI) and glycemic load (GL), and the risk of Type 2 Diabetes.

Researchers followed 164,659 women from 1991-2008 that took part in the Nurses Health Studies I and II, and 40, 498 men from the Health Professionals Follow-Up Study. All were free of diabetes, cardiovascular disease and cancer at the beginning of the study periods. Periodic questionnaires were used to analyze diet and lifestyle.  The researchers updated a meta-analysis which also included the results from the 3 cohort studies.

After compiling the results of the 3 population studies, it was found that the adults with diets in the highest quintile (20%) of energy-adjusted GI had a 33% higher risk of T2D than those with diets in the lowest 20% of GI. Subjects in the highest GL group had a 10% higher risk of T2D than those in the lowest group. Consumption of a combination diet that was high in GI or GL but low in cereal fiber had a 50% greater risk of T2D. When comparing the highest with lowest categories of GI and GL in the updated meta-analysis researcher found an increased risk of T2D of 19% and 13% respectively.   

The results from these studies confirm that consuming a high-GI/GL diet is associated with a higher risk of Type 2 Diabetes, especially when cereal fiber intake is also low.

Shilpa N Bhupathiraju et al.  Glycemic index, glycemic load, and risk of type 2 diabetes: results from 3 large US cohorts and an updated meta-analysis.  Am J Clin Nutr.  First published April 30, 2014, doi: 10.3945/ajcn.113.079533 [Epub ahead of print].