HealthDay News — Eating more legumes, such as beans and lentils, improved glycemic control and lowered total cholesterol and triglycerides in patients with type 2 diabetes, study results show.

Patients who consumed an additional cup of legumes per day had a greater reduction in HbA1c than patients who increased their insoluble fiber consumption for 3 months (-0.5% vs. -0.3%, P<0.001), David Jenkins, MD, PhD, of the University of Toronto, and colleagues reported online in the Archives of Internal Medicine.

Although legumes are known as a low glycemic index food and have been recommended in nutrition guidelines developed for patients with diabetes, few studies have assessed the food’s affect on glycemic control and other diabetes risk factors.

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So Jenkins and colleagues enrolled 121 patients with type 2 diabetes and randomly assigned patients to one of two diets for three months — a low glycemic index legume diet that required participants to eat at least one cup of legumes per day, or a diet that required participants to increase their insoluble fiber intake via consumping whole wheat products. The primary outcome was change in HbA1c, with a secondary outcome of coronary heart disease risk.

The researchers found that the low-GI legume diet correlated with a 0.5% reduction in HbA1c values, while the high wheat fiber diet correlated with a 0.3% reduction in HbA1c values. The relative reduction was significantly greater for the low-GI legume group compared with the high wheat fiber diet, even after adjusting for body weight change (P=0.005).

In the low-GI legume diet group, the coronary heart disease risk reduction was 0.8% (P=0.003), which was mainly due to a greater reduction in systolic blood pressure with the low-GI legume vs. the high wheat fiber diet.

The legume diet also significantly lowered mean total cholesterol (-8 mg/dL, P<0.001) and triglycerides (-22 mg/dL, P<0.001), without any changes in HDL cholesterol levels.

“In conclusion, legume consumption of approximately 190 g per day (one cup) seems to contribute usefully to a low-GI diet and reduce coronary heart disease risk through a reduction in blood pressure,” the researchers wrote.

In an accompanying editorial, Marion Franz, MS, RD, acknowledged that although legumes are a part of a healthy diet for people with diabetes and the general population, she questioned whether the modest benefits observed in the study were attributable to the legumes or reduced overall energy intake.

She wrote, “whether people with diabetes can eat the amount necessary to improve glycemic control is debatable, and, if legumes do improve glycemia, is it because of their low GI or high soluble fiber content?”

Franz emphasized that just as certain patients may respond better to different diabetes medications or insulin regimens, there is no one-sized fits all approach to nutrition therapy.


  1. Jenkins DJA et al. Arch Intern Med. 2012; DOI: 10.1001/2013.jamainternmed.70.
  2. Franz MJ. Arch Intern Med. 2012; DOI: 10.1001/2013.jamainternmed.871