H.J. HUHNT, R. ZICK, H.J. MITZKAT, A. VON ZUR MÜHLEN and M.J. MÜLLER
E. MARTENS, R. ZICK, H. J. MITZKAT, A. VON ZUR MÜHLEN and M. J. MÜLLER
E. MARTENS, A. V. Z. MÜHLEN, R. ZICK, H.J. MITZKAT and M.J. MÜLLER
E. Martens, R. Zick, H. J. Mitzkat, A. von zur Mühlen and M. J. Müller
Abstract. The effect of hyperglycemia on insulin-induced glucose metabolism (M) was investigated in healthy subjects using sequential clamp protocols at constant insulin + somatostatin infusions and varying plasma glucose. During euglycemia (4.8 mmol/l) M increased from 5.6 to 12.5 mg·kg−1·min−1 with increasing plasma insulin (0.34-3.00 nmol/l). At increasing glucose (6.7 mmol/l), M further increased (9.7 to 19.2 mg·kg−1·min−1) with the plasma insulin level (0.41 to 2.99 nmol/l). At a plasma glucose level of 9.8 mmol/l insulin (0.42 to 3.17 nmol/l) was still effective to increase M (13.7 to 25.2 mg·kg−1·min−1). Regression analysis showed that hyperglycemia does not only increase the maximal insulin-stimulated M, but also decreases the insulin concentration causing a half maximum effect. During prolonged clamp studies M increased by about 10% per h, independent by the plasma glucose level. We conclude that hyperglycemia increases M by increasing insulin responsiveness as well as insulin sensitivity. Data derived from euglycemic clamp studies alone are of limited value with respect to the assessment of insulin action.