Non-insulin-mediated glucose uptake in several insulin-resistant states in the postabsortive period

The aim of our work was to study non-insulin-mediated glucose uptake (NIMGU), in the postabsorptive state, in several pathologies characterized by peripheral insulin resistance, namely, obesity (n = 10), NIDDM (n = 7), acromegaly (n = 7) and Cushing's disease (n = 6). These groups were compared with a group of 16 healthy subjects. To estimate peripheral insulin sensitivity (SI) and glucose effectiveness (SG), we used the minimal model of glucose metabolism. Although all of these pathologies showed severe insulin resistance (control: 6.44 +/- 2.63, obesity: 2.84 +/- 1.57, NIDDM: 1.71 +/- 0.77, acromegaly: 1.88 +/- 1.23, Cushing's disease: 1.87 +/- 0.66 x 10(-4) min-1 (microU/ml)-1, P < 0.01), fasting insulin-mediated glucose uptake (IMGU) did not differ significantly among the five groups, because reactive hyperinsulinaemia was present in all of these states. The contribution of NIMGU to whole-body glucose uptake did not differ significantly among the five groups (control: 77 +/- 8%; obesity: 77 +/- 9%; acromegaly: 82 +/- 8%; Cushing's disease: 83 +/- 8%; NIDDM: 84 +/- 7%). In conclusion, our data show that, in the postabsorptive period, non-insulin mediated glucose uptake is a major determinant of glucose disposal and is similar in the different pathologies studied; on the other hand, although absolute rates of basal insulin-mediated glucose uptake are reduced in insulin-resistant states, they did not achieve statistical value compared with control subjects because of compensatory hyperinsulinaemia.