Dipeptidyl peptidase (DPP-IV) rapidly metabolises hormones such as glucagon-like peptide-1(7-36)amide. This study evaluated circulating DPP-IV activity in type 2 diabetic patients in relation to GLP-1 degradation and metabolic control. Blood samples were collected from type 2 diabetic patients in three main categories: good glycaemic control (HbA(1c) 9%). Age- and sex-matched non-diabetic subjects were used as controls. Circulating DPP-IV activity of healthy control subjects was 22.5 +/- 0.7 nmol/ml/min (n = 70). In the combined groups of type 2 diabetic subjects, circulating DPP-IV activity was significantly decreased at 18.1 +/- 0.7 nmol/ml/min (p <0.001, n = 54). DPP-IV activity was negatively correlated with both glucose (p <0.01) and HbA(1c) (p <0.01) in this population. Furthermore, DPP-IV activity was reduced 1.2-fold (p <0.01, n = 25), 1.3-fold (p <0.001, n = 19) and 1.3-fold (p <0.05, n =10) in good, moderate and poorly controlled diabetic groups, 18.7 +/- 1.0, 17.4 +/- 1.4 and 18.0 +/- 1.5 nmol/ml/min, respectively. Degradation of GLP-1 by in vitro incubation with pooled plasma samples from healthy and type 2 diabetic subjects revealed decreased degradation to the inactive metabolite, GLP-1(9-36), in the diabetic group. These data indicate decreased DPP-IV activity and GLP-1 degradation in type 2 diabetes. DPP-IV enzyme activity appears to be depressed in response to poor glycaemic control. (c). 2007 Elsevier Ireland Ltd. All rights reserved.
McKillop, A., Duffy, N. A., Lindsay, J. R., O'Harte, F., Bell, P. M., & Flatt, P. (2008). Decreased dipeptidyl peptidase-IV activity and glucagon-like peptide-1(7-36)amide degradation in type 2 diabetic subjects. Diabetes Research and Clinical Practice, 79(1), 79-85. https://doi.org/10.1016/j.diabres.2007.08.001