To the Editor In the OmniCarb randomized clinical trial, Dr Sacks and colleagues1 concluded that a 5-week, low glycemic index version of the Dietary Approaches to Stop Hypertension diet did not improve insulin sensitivity or cardiovascular risk factors compared with a higher glycemic index diet.
We are concerned that the duration of the trial was too short. Longer 12- to 26-week studies have demonstrated that low glycemic index diets progressively enhance glycemic control2 and insulin sensitivity.3 High-density lipoprotein (HDL) cholesterol level can increase while patients are on low glycemic index diets over time (approximately 10 weeks).4 Weight loss maintenance and levels of low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) also were improved in overweight and obese participants in the Diet, Obesity, and Genes (DIOGENES) study (26 weeks).5
Brand-Miller JC, Astrup A, Buyken AE. Low vs High Glycemic Index Diet. JAMA. 2015;313(13):1371-1372. doi:10.1001/jama.2015.2078