Effect of whole grains on insulin sensitivity in overweight hyperinsulinemic adults

Am J Clin Nutr. 2002 May;75(5):848-55. doi: 10.1093/ajcn/75.5.848.


Background: Epidemiologic studies have found whole-grain intake to be inversely associated with the risk of type 2 diabetes and heart disease.

Objective: We tested the hypothesis that whole-grain consumption improves insulin sensitivity in overweight and obese adults.

Design: This controlled experiment compared insulin sensitivity between diets (55% carbohydrate, 30% fat) including 6-10 servings/d of breakfast cereal, bread, rice, pasta, muffins, cookies, and snacks of either whole or refined grains. Total energy needs were estimated to maintain body weight. Eleven overweight or obese [body mass index (in kg/m(2)): 27-36] hyperinsulinemic adults aged 25-56 y participated in a randomized crossover design. At the end of each 6-wk diet period, the subjects consumed 355 mL (12 oz) of a liquid mixed meal, and blood samples were taken over 2 h. The next day a euglycemic hyperinsulinemic clamp test was administered.

Results: Fasting insulin was 10% lower during consumption of the whole-grain than during consumption of the refined-grain diet (mean difference: -15 +/- 5.5 pmol/L; P = 0.03). After the whole-grain diet, the area under the 2-h insulin curve tended to be lower (-8832 pmol.min/L; 95% CI: -18720, 1062) than after the refined-grain diet. The rate of glucose infusion during the final 30 min of the clamp test was higher after the whole-grain diet (0.07 x 10(-4) mmol.kg(-1).min(-1) per pmol/L; 95% CI: 0.003 x 10(-4), 0.144 x 10(-4)).

Conclusion: Insulin sensitivity may be an important mechanism whereby whole-grain foods reduce the risk of type 2 diabetes and heart disease.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Body Weight
  • Cross-Over Studies
  • Diet* / adverse effects
  • Edible Grain*
  • Fasting / blood
  • Female
  • Glucose Clamp Technique
  • Homeostasis
  • Humans
  • Hyperinsulinism / physiopathology*
  • Insulin / blood
  • Insulin Resistance / physiology*
  • Male
  • Obesity / complications*
  • Obesity / physiopathology*
  • Postprandial Period
  • Satiety Response


  • Insulin