Plasma Ghrelin Levels After Two High-carbohydrate Meals Producing Different Insulin Responses in Patients with Metabolic Syndrome

Ghrelin is an orexigenic peptide produced in the stomach and its plasma levels are decreased acutely in response to ingested nutrients. To further clarify the role of insulin on ghrelin secretion, the present study was designed to investigate whether circulating ghrelin is affected differently by two mixtures of whole-grain breads known to produce low or high insulin responses in obese non-diabetic subjects with metabolic syndrome. After an overnight fast eight obese subjects with the metabolic syndrome (3 men and 5 women; BMI 33.7+/-0.7 kg/m(2); age 55.6+/-1.8 y) received two different meals consisting of whole-grain rye or wheat breads. The comparison group (3 men and 5 women; BMI 22.5+/-0.5 kg/m(2); age 26.0+/-0.9 y) received a wheat bread meal. Blood samples were collected postprandially at time intervals for 2 h. Feelings of hunger and satiety were analyzed using the visual analogue scales. Ghrelin concentrations decreased after bread meals in lean individuals, but not in obese individuals with the metabolic syndrome. Despite the difference in plasma insulin response, there was no difference in plasma ghrelin or feelings of hunger and satiety in patients with metabolic syndrome. After both rye and wheat bread meals, the decrease in ghrelin concentrations seen in normal-weight individuals after wheat bread meal was absent in subjects with metabolic syndrome. Despite the different plasma insulin response in obese patients, ghrelin levels did not change in response to either type of bread meals. In addition, ghrelin levels did not correlate with insulin, glucose, HOMA1-IR and satiety and hunger ratings in either study groups. This indicates that regulation of ghrelin might be altered in obese patients with metabolic syndrome independently of insulin.