Structure, antihyperglycemic activity and cellular actions of a novel diglycated human insulin

Human insulin was glycated under hyperglycemic reducing conditions and a no vel diglycated form (M-r 6135.1 Da) was purified by RP-HPLC. Endoproteinase Glu-C digestion combined with mass spectrometry and automated Edman degrad ation localized glycation to Gly(1) and Phe(1) of the insulin A- and B-chai ns, respectively. Intraperitoneal (i.p.) administration of diglycated insul in to mice alone or in combination with glucose (7 nmol/kg) resulted in a 4 3-61% and 11-34% reduction in glucose lowering activity, respectively, comp ared with native insulin. Consistent with these findings, diglycated insuli n (10(-9) to 10(-7) mol/liter) was 22-38% less effective (P < 0.001) than n ative insulin in stimulating glucose uptake, glucose oxidation and glycogen production in isolated mouse abdominal muscle. (C) 2000 Elsevier Science I nc. All rights reserved.