Five groups were examined: healthy control subjects, first-degree relatives of subjects with type 2 diabetes, subjects with impaired glucose tolerance (IGT), subjects with type 2 diabetes and postprandial hyperglycemia but normal fasting plasma glucose levels (diabetes group A [DMA]), and subjects with type 2 diabetes with both postprandial and fasting hyperglycemia (diabetes group B [DMB]).ATBF was measured with (133)Xe.