OBJECTIVE: We investigated the changes in subcutaneous adipose tissue blood flow (ATBF) after a meal in the various stages of type 2 diabetes. RESEARCH DESIGN AND METHODS: 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. RESULTS: ATBF was higher in control subjects (1,507 +/- 103 ml/100 cm(3) tissue x min) versus relatives and IGT, DMA, and DMB subjects (845 +/- 123, 679 +/- 69, 765 +/- 60, and 757 +/- 69 ml/100 cm(3) tissue x min, respectively; P < 0.001). Insulin sensitivity index (ISI) in control subjects (82 +/- 3 mg x l(2)/mmol x mU x min) was higher versus that for relatives and IGT, DMA, and DMB subjects (60 +/- 3, 45 +/- 1, 40 +/- 6, and 29 +/- 4 mg x l(2)/mmol x mU x min, respectively; P < 0.0001). ISI was positively associated with peak-baseline ATBF (beta coefficient 0.029 +/- 0.013, P = 0.03). CONCLUSIONS: After meal ingestion, insulin-stimulated ATBF was decreased in relatives and and IGT, DMA, and DMB subjects. This defect could be an early marker of insulin resistance that precedes the development of type 2 diabetes.