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

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.