Effect of linagliptin, alone and in combination with voglibose or exendin-4, on glucose control in male ZDF rats

The effects of the dipeptidyl peptidase-4 (DPP-4) inhibitor, linagliptin, alone and in combination with voglibose or exendin-4, on glycaemic control and body weight were assessed in an animal model of type 2 diabetes. Voglibose is an alpha-glucosidase inhibitor but also increases glucagon-like peptide 1 (GLP-1). Exendin-4 is a GLP-1 receptor agonist. Male Zucker Diabetic Fatty (ZDF) rats were dosed for 3 days, fasted overnight and a sucrose/glucose tolerance test was performed. Linagliptin (1 mg/kg po) improved glucose tolerance by increasing plasma GLP-1 (active) and insulin secretion, whilst having no effect on body weight. Voglibose (1 and 10 mg/kg po) reduced body weight, improved glycaemic control, reduced plasma insulin and increased total but not active GLP-1. The combination of linagliptin and voglibose significantly reduced body weight, improved glycaemic control and reduced plasma insulin compared to linagliptin alone. Furthermore, linagliptin plus voglibose produced a marked increase in GLP-1 (active) at 5 min post-sucrose, compared to linagliptin, possibly because linagliptin prevented the degradation of GLP-1 secreted in response to voglibose. Exendin-4 (10 mu g/kg sc) significantly reduced body weight, improved glucose tolerance but reduced GLP-1 (active). The combination of linagliptin and exendin-4 significantly reduced body weight and improved glycaemic control but had no effect on plasma GLP-1. Overall it did not markedly improve glycaemic control compared to the individual drugs. The improved glucose control, reduced body weight and markedly increased plasma GLP-1 levels in animals given linagliptin with voglibose, suggests that this combination may be particularly beneficial in the treatment of type 2 diabetes. (C) 2014 The Authors. Published by Elsevier By This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).