Ghrelin Levels in Basal Conditions and During Glucose Tolerance Test in Prediabetic and Diabetic Patients

Abstract

Ghrelin is associated with glucose homeostasis but its’ possible relevance with glucose levels in physiological and pathological conditions has so far been poorly investigated. The aim of the present study was to evaluate circulating ghrelin levels in prediabetic and diabetic patients in basal conditions and in response to oral glucose tolerance test (OGTT). A total of 90 male adults aged 40 – 73 years old were enrolled in our study. Fasting and postprandial plasma ghrelin, insulin and glucose levels were measured at 0, 60, 120 and 180 min following an OGTT in 40 patients with type 2 diabetes mellitus (T2DM), 20 with impaired glucose tolerance (IGT) and 30 controls. Incremental and total area under response curve were determined and calculated for glucose, insulin and ghrelin. Fasting plasma ghrelin concentrations were significantly lower in the T2DM group than IGT and control group patients (p<0.01) but not between healthy subjects and IGT group (p=0.746). In the diabetics’ group ghrelin levels showed a statistically significant negative correlation with insulin and a positive correlation with HbA1c and glucose. At all time points after the OGTT ghrelin concentrations were significantly lower in the T2DM group compared to IGT group and controls. Plasma ghrelin concentrations are lower in male diabetic patients at the fasting state and remain lower at all time points after an OGTT while minor differences were found between normal and IGT subjects. Ghrelin might play a role in insulin and glucose metabolism in diabetic patients but not in patients with IGT.

Subjects with high fasting insulin also have higher postprandial GLP-1 and glucagon levels than controls with lower insulin

“…Ghrelin responses did not differ between the two groups. This confirms earlier findings that the levels are similar in subjects with or without impaired glucose tolerance [22] and with or without obesity [9]. Levels of glucagon are generally elevated in patients with insulin resistance and type 2 diabetes [5,14,16,23].…”

Obestatin Levels in Basal Conditions and During Oral Glucose Tolerance Test in male subjects with Prediabetes and Diabetes

“…On the other side the ghrelin peptide, as encoded by the same preproghrelin gene which produce the opposite peptide obestatin, it seems to play a crucial role in glucose and insulin metabolism and in development of obesity and DMT2. In our previous work [44], which included a partially overlapped population we observed that both peptides in fasting condition appear with lower levels in subjects with diabetes compare to controls, but not in prediabetics. In terms of comparison with other variables such as glucose, insulin and triglycerides in subjects with diabetes in both peptides we observed that they were inversely correlated with each peptide, concluding that ghrelin and obestatin behave differently in people with diabetes.…”

Association of ghrelin dynamics with beta cell function in Japanese subjects with normal glucose tolerance

“…In clinical studies, fasting ghrelin concentration was low in obese individuals, and ghrelin concentrations decreased after nutrient loading . While exogenous ghrelin administration in humans was shown to inhibit β and worsen glucose tolerance, few studies have reported the relationship between ghrelin secretion and β during the OGTT …”

“…18 While exogenous ghrelin administration in humans was shown to inhibit β and worsen glucose tolerance, 19,20 few studies have reported the relationship between ghrelin secretion and β during the OGTT. 21 The present study tested the hypothesis that, in the OGTT, ghrelin dynamics are associated with β. The relationship between SI and β was first analyzed in young subjects with NGT, and indicators to determine DI were obtained.…”