Effect of legumes as part of a low glycemic index diet on glycemic control and cardiovascular risk factors in type 2 diabetes mellitus: a randomized controlled trial

Arch Intern Med. 2012 Nov 26;172(21):1653-60. doi: 10.1001/2013.jamainternmed.70.


Background: Legumes, including beans, chickpeas, and lentils, are among the lowest glycemic index (GI) foods and have been recommended in national diabetes mellitus (DM) guidelines. Yet, to our knowledge, they have never been used specifically to lower the GI of the diet. We have therefore undertaken a study of low-GI foods in type 2 DM with a focus on legumes in the intervention.

Methods: A total of 121 participants with type 2 DM were randomized to either a low-GI legume diet that encouraged participants to increase legume intake by at least 1 cup per day, or to increase insoluble fiber by consumption of whole wheat products, for 3 months. The primary outcome was change in hemoglobin A1c (HbA1c) values with calculated coronary heart disease (CHD) risk score as a secondary outcome.

Results: The low-GI legume diet reduced HbA1c values by -0.5% (95% CI, -0.6% to -0.4%) and the high wheat fiber diet reduced HbA1c values by -0.3% (95% CI, -0.4% to -0.2%). The relative reduction in HbA1c values after the low-GI legume diet was greater than after the high wheat fiber diet by -0.2% (95% CI, -0.3% to -0.1%; P < .001). The respective CHD risk reduction on the low-GI legume diet was -0.8% (95% CI, -1.4% to -0.3%; P = .003), largely owing to a greater relative reduction in systolic blood pressure on the low-GI legume diet compared with the high wheat fiber diet (-4.5 mm Hg; 95% CI, -7.0 to -2.1 mm Hg; P < .001).

Conclusion: Incorporation of legumes as part of a low-GI diet improved both glycemic control and reduced calculated CHD risk score in type 2 DM.

Trial registration: ClinicalTrials.gov NCT01063361.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / metabolism*
  • Cardiovascular Diseases / etiology*
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / complications
  • Diabetes Mellitus, Type 2 / diet therapy*
  • Diet, Diabetic / methods*
  • Dietary Fiber
  • Fabaceae*
  • Female
  • Glycated Hemoglobin / metabolism
  • Glycemic Index
  • Humans
  • Male
  • Middle Aged
  • Risk Factors
  • Treatment Outcome


  • Blood Glucose
  • Dietary Fiber
  • Glycated Hemoglobin A

Associated data

  • ClinicalTrials.gov/NCT01063361