The OGTT has been carried out by the authors with 25 older individuals (age 82 +/- 5.1) and 14 younger persons (age 28 +/- 9.0) who all showed neither clinical nor laboratory symptoms of apparent diabetes. During the test authors were determining venose glycaemia, insulin, C-peptide, glucagon and they computed some mathematical quantities enabling the estimation of the insulin secretion. The course of the OGTT of the older group showed higher values of glycaemia, insulin and C-peptide since the 60th minute tending to a duration or to a slow decline (up to the 120th minute). A significant difference in the glucagon values was found by the authors only in the case of fasting higher with the older ones (p = 0.01). The estimation of insulin secretion in the early phase of the OGTT was found by the authors significantly higher with the younger ones in both times.