Disturbances in dynamics of glucose, insulin and C-peptide in blood after a normalized intake of mixed meal in obesity and type 2 diabetes mellitus

Abstract

The aim of the study is to investigate the dynamics of venous blood glucose, insulin, and C-peptide in response to intake a meal normalized to body mass in obese patients without and with type 2 diabetes mellitus. Venous blood samples were taken from 7 healthy subjects, 9 obese patients, and 10 obese patients with type 2 diabetes mellitus (mean period of diagnosed diabetes 7 years) before and 30, 60, 90, 120, and 180 min after a mixed meal (6 kcal/kg of body mass); additionally, 9 patients with obesity and type 2 diabetes mellitus and 3 healthy volunteers completed a hyperinsulinemic euglycemic clamp test. In patient groups the energy content of food did not differ, but was 1.8 times higher than in the control. An increase in glucose level one hour after a meal was maximal in patients with type 2 diabetes, but an increase in insulin and C-peptide — in obese patients, that related to impairment of insulin-dependent glucose uptake by tissues and of the rate of insulin secretion (dysfunction of â-cells) in patients. At the same time, an increase in the total area under the curve “C-peptide–time” shows that the maximum secretory response of â-cells is comparable in obese patients without and with type 2 diabetes mellitus. The absolute blood glucose level 90 minutes after a meal was closely correlated with the M-index — the marker of systemic sensitivity to insulin (rs = –0.82, p = 0.002). Our results characterize the features in the regulation of carbohydrate metabolism after intake a mixed meal, normalized to body mass, in people with the varying severity of metabolic disorders, and open up prospects for a wider application of this test in practice.