The aim of the present study was to investigate the secretion and hepatic removal of insulin in the healthy offspring of type 2 (non-insulin-dependent) diabetic subjects. For this purpose, we examined the insulin and C-peptide responses to a 75 g oral glucose tolerance test in a group of 55 healthy subjects each having one parent with type 2 diabetes mellitus, and in a group of 55 individuals without a family history of diabetes. All the 110 subjects in the study were ambulatory volunteers, in good general health, and with normal glucose tolerance. The two groups were carefully matched for sex, age, and body weight. Glucose and insulin concentrations as well as incremental areas were similar in the two groups. C-peptide levels and incremental areas were almost identical. C-peptide to insulin molar ratios both in fasting state and after glucose load, as well as relations between C-peptide and insulin incremental areas did not differ in the two groups. In conclusion, the healthy offspring of only one non-insulin-dependent diabetic parent show a normal beta-cell response to glucose, and normal removal of insulin by the liver.