Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. A diet with a high glycemic index was associated with an increased risk of death and cardiovascular disease.

2. Among those without preexisting cardiovascular disease, a high glycemic load was not associated with increased death.

Evidence Rating Level: 2 (Good)

Study Rundown:

Foods with a high glycemic index (GI) raise blood glucose levels faster than lower GI food. Previous studies have shown their importance in diabetes care; however, data is inconclusive on the impact of high GI on cardiovascular disease and mortality. As such, this study surveyed participants on their dietary habits, baseline demographic factors, lifestyle, health history, major cardiovascular events, and death. The study determined a high glycemic index diet was associated with an increased risk of major cardiovascular events and deaths irrespective of baseline cardiovascular disease status. However, a higher glycemic load was only associated with cardiovascular events and death for those with preexisting cardiovascular disease. There were several limitations in the study, for example, due to the diverse nature of the study populations, carbohydrate foods were grouped into seven broad categories which limited the precision in the calculation of the glycemic index. Overall, this study indicates a likely association between increased cardiovascular disease and a high glycemic index diet.

In-Depth [prospective cohort]:

This was a multinational, prospective, observational cohort study that enrolled 137,851 participants in 20 countries. Participants aged 35 to 70 years of age were included in the study. Participants with improbable baseline energy intake were excluded from the study. The primary outcome was a composite of major cardiovascular events consisting of cardiovascular death, nonfatal myocardial infarction, stroke, and heart failure. The median follow-up time was 9.5 years, and there were 8,780 deaths and 8,252 major cardiovascular events. Using multivariable Cox frailty analysis, a high glycemic diet was associated with increased cardiovascular disease or death for those with preexisting cardiovascular disease (hazard ratio [HR], 1.51; 95% confidence interval [CI], 1.25-1.82) and those without (HR, 1.21; 95% CI, 1.11-1.34). Overall, the large and diverse population likely showed that there are some mortality and cardiovascular benefits of a diet with a low glycemic index that is consistent with previous studies.

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